Use qtpy, deprecate superqt.qtcompat, drop support for Qt <5.12

[tlambert03]

PR that will remove qtcompat and use qtpy again once the qt6 support is realeased.

[codecov-commenter]

Codecov Report

Merging #39 (925667f) into main (bbd60ee) will decrease coverage by 0.27%.
The diff coverage is 87.50%.

@@            Coverage Diff             @@
##             main      #39      +/-   ##
==========================================
- Coverage   84.83%   84.55%   -0.28%     
==========================================
  Files          27       24       -3     
  Lines        2169     2104      -65     
==========================================
- Hits         1840     1779      -61     
+ Misses        329      325       -4     

Impacted Files	Coverage Δ
src/superqt/fonticon/__init__.py	88.88% <ø> (ø)
src/superqt/qtcompat/__init__.py	0.00% <0.00%> (-72.92%)	⬇️
src/superqt/_eliding_label.py	100.00% <100.00%> (ø)
src/superqt/collapsible/_collapsible.py	97.18% <100.00%> (ø)
src/superqt/combobox/_enum_combobox.py	93.84% <100.00%> (ø)
src/superqt/fonticon/_animations.py	100.00% <100.00%> (ø)
src/superqt/fonticon/_qfont_icon.py	93.43% <100.00%> (ø)
src/superqt/sliders/_generic_range_slider.py	89.00% <100.00%> (ø)
src/superqt/sliders/_generic_slider.py	89.13% <100.00%> (-0.32%)	⬇️
src/superqt/sliders/_labeled.py	82.47% <100.00%> (ø)
... and 8 more

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[tlambert03]

this still needs spyder-ide/qtpy#276 and spyder-ide/qtpy#271 before we could use qtpy again

[Czaki]

add minimal version requirement, Without this update of superqt will not force update of qtpy, so compatibility with PySide6/PyQt6 will be missed.

[tlambert03]

Hmmm, I hesitate to do that in case someone wanted to use an older version of qtpy with qt 5.15?

Its not that superqt required 2.0+, it's that PyQt6 does... So it could make some environment resolutions more difficult if we do that.

Thoughts?

[Czaki]

is there release from the time of introduction qtcompat? If yes hen someone may have code that uses superqt, and have an older version of qtpy in the environment, then after the update, the code will be broken. But maybe this is enough small that put information in readme will be enough.