fix: Deck creation UI on Anki qt6 on MacOS

[RisingOrange]

On Anki versions higher than 2.1.66 on Qt6 it’s not possible to create an AnkiHub deck. When the user selects a deck and confirms, nothing happens.
The forum post linked below includes a video that shows when the problem happens.

This PR attempts to fix this problem.

Related issues

Fix UI for creating deck on Anki ≥ 21.66 Qt6
Report on the forum: https://community.ankihub.net/t/cant-upload-new-collaborative-decks-on-qt6/2340

Proposed changes

• According to this issue in the Anki repo, calling StudyDeck.exec() is likely causing the problem. (StudyDeck is the deck chooser dialog). To solve this problem a callback argument was added to StudyDeck. When this callback argument is passed, show() is used instead of exec() to show the dialog.
  https://github.com/ankitects/anki/blob/ae6a03942f651790c40f8d8479f90eb7715bf2af/qt/aqt/studydeck.py#L98-L101
  Our code is now also using this callback argument. This should fix the problem.
• Update tests

How to reproduce

The bug was reported by users who were using the Qt6 version of Anki >= 2.1.60 on MacOS.

[codecov]

Codecov Report

Merging #799 (2f8c738) into main (545809a) will not change coverage.
The diff coverage is 100.00%.

❗ Current head 2f8c738 differs from pull request most recent head d5cfec5. Consider uploading reports for the commit d5cfec5 to get more accurate results

@@           Coverage Diff           @@
##             main     #799   +/-   ##
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  Coverage   81.94%   81.94%           
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  Files          64       64           
  Lines        5743     5743           
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  Hits         4706     4706           
  Misses       1037     1037           

Files	Coverage Δ
ankihub/gui/operations/deck_creation.py	80.00% <100.00%> (ø)

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