Has any country ever diverted an international flight in order to arrest a wanted person?

One instance from 1954, Syrian plane captured by Israel:

TEL AVIV, Israel, Dec. 12 -A Syrian Airways Dakota was intercepted by Israeli fighter planes this morning and escorted to Lydda Airport. Four passengers' and five crew members were detained, but one passenger, an American citizen, was released.

Second instance from 2010, involving a flight from Paris to Mexico City being forcefully diverted to Montreal:

The passenger removed from an Aeromexico flight diverted to Montreal has been sent to the U.S., Canadian and American officials say.
Abdirahman Ali Gaal was removed from the flight bound for Mexico City from Paris on Sunday at the request of U.S. officials.
The Canada Border Services Agency and the U.S. Department of Homeland Security confirmed that he was turned over to U.S. officials at 4 p.m. Tuesday.

Third instance from 2016 is related to a flight from Kiev to Minsk being grounded before it could reach the Belarus border:

A Belarusian “Belavia” aircraft, en route from Kiev to Minsk, was forced to return to the Ukrainian airport under the threat of being intercepted by military jets. The reason of the forced landing was an Armenian citizen aboard the aircraft, Obozrevatel.com reported citing the airline’s press service.

“The ground controller ordered the aircraft to immediately return to the airport after entering the airspace of Belarus 50km. No explanation was given. The ground controller reported in case of failing to fulfill the order fighter jets will be scrambled”, the statement of the airline company reads.

There's an article published by the BBC today on this very topic. It quotes three of the examples listed in the accepted answer, and this one from 1956:

1956: The arrest of the leaders of the Algerian independence movement

On 22 October 1956 five leaders of the Algerian independence movement, the FLN, were on a civilian flight from Rabat in Morocco to Tunis, reports BBC Arabic's Ahmed Rouaba. They were due to take part in a conference on the future of the Maghreb region hosted by then Tunisian President Habib Bourguiba.

Algeria was a French colony at the time and the French secret service sent fighter jets to intercept the passenger plane, forcing it to land in Algeria.

The events sparked anger in Morocco and Tunisia.

The five arrested included Ahmed Ben Bella, who went on to be Algeria's first president after it gained independence from France. He died in 2012 aged 95.

The same article notably says the Evo Morales grounding incident is not directly comparable, since 1) the aircraft wasn't forced to land by military interceptors, but rather by the airspace being closed, and 2) it was a state aircraft and not a civilian one that was involved. State aircraft are not covered by the Chicago convention.

Interception of EgyptAir jet:

• Terrorists murdered a US citizen
• Egypt let the terrorists fly out on a commercial (chartered) airplane
• US intercepted the flight in international airspace and made it land in Italy
• Italians released the mastermind but tried the terrorists (calling them "soldiers fighting for their ideals")

In 2013, Bolivia president's jet heading from Moscow, Russia was rerouted and forced to land in Austria in search for Edward Snowden;

• Bolivian president’s plane forced to land in Austria in hunt for Snowden — The Washington Post
• Evo Morales grounding incident — Wikipedia

I'll note here that the Morales' plane story is much more complicated that it's made to be in the other answer. It was apparently a false flag operation to a good extent, misleading the Westerners as to whom was on-board; or at least Assange claimed he did that. Anyway, the Morales plane landed in Austria because its crew claimed it could not read its fuel gauges:

Control tower: Do you need any assistance?

Pilot: Not at this moment. We need to land because we cannot get a correct indication of the fuel indication so as a precaution we need to land.

Why the plane landed in Austria isn't clear, but it doesn't seem to have been at the insistence of the Austrians.

Then Morales declared outrage for being "forced" to land.

The issue whether the plane was actually denied airspace entry (and by whom) is a bit more murky. At least France clearly apologized, but Spain the plane was actually due to land for refueling (Canary Islands, actually) never made a clear statement. It is known that Portugal granted overflight some days before, but refused the request to refuel on their territory. (I'll spare you the quotes on that.) So it's not really a clear-cut situation like a jet fighter showing up and requesting the plane land.

Also the reports whether the Morales' plane was searched are fairly contradictory. An Austrian minister initially said yes, but after Bolivians denied that took place, the details came out as:

"Someone from the airport staff sought out the aircraft or the pilot after landing to inquire about the nature of the technical problem," [Austrian President Heinz] Fischer was quoted as saying.

"The Austrian official was advised that the defect was already fixed, and saw on this occasion that the plane was empty... He did not look under the seats. There was no formal inspection, but no other people were found on board," Fischer added.

Pressed on whether that meant Austrians had not searched the plane, he said, "There was no search in the forensic sense. There was also no reason to under international law. The plane of a president belongs to 'his territory' and cannot be searched readily."

N.B. Assange was aware of this too, as in the interview (first link) he said:

from a legal perspective, they are flying embassies.

On the other hand, that does not mean countries have to allow them:

Eurocontrol - which co-ordinates Europe's airspace and traffic control - said it was "a national decision whether or not to accept a state flight" under the terms of the Chicago Convention on International Civil Aviation.

But there's a [legal] difference between not allowing a flight to enter and forcing it to land.