QtPy 2.3.0 on Python PyPI

What's Changed

PR: Add Qsci to the imports by @dgoeries in #372
Don't re-assign Qt.MouseButton.MiddleButton on PySide6 by @astrofrog in #374
PR: Try PySide6 on conda by @jschueller in #378
PR: Enable more qt6 tests by @jschueller in #380
PR: Expand the CI test matrix with Qt/bindings 6.4 and fix tests with PyQt 5.9 by @CAM-Gerlach in #376
PR: Add QtPdf and QtPdfWidgets by @jschueller in #382
PR: Raise error when no bindings are found at __init__ by @dalthviz in #379

Full Changelog: v2.2.1...v2.3.0