chore(deps): make Qt backend optional (#350)

* chore(deps): make Qt backend optional

TODO:
- [ ] Add relevant entry in CHANGELOG
- [ ] Update install documentation
- [ ] Make sure `manim-slides convert` can run without any Qt backend
- [ ] Make sure test suite works (partially) without any Qt backend
- [ ] Make sure we can import `manim_slides` without any Qt backend

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* chore(deps): some fixes but wip

* chore(docs): update

* chore(deps): support PyQt6

* chore(deps): make Qt backend optional

TODO:
- [ ] Add relevant entry in CHANGELOG
- [ ] Update install documentation
- [ ] Make sure `manim-slides convert` can run without any Qt backend
- [ ] Make sure test suite works (partially) without any Qt backend
- [ ] Make sure we can import `manim_slides` without any Qt backend

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* chore(deps): some fixes but wip

* chore(docs): update

* chore(deps): support PyQt6

* fix(deps): ci and docs

* fix(lib): missing package

* chore(ci): does it work?

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* chore(test): skip failing

* chore(docs): update

* chore(docs): update

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* fix(docs): typo

* fix(test): quit instead of shutdown

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

tests/test_wizard.py

@@ -1,17 +1,18 @@
 from pathlib import Path
 
 from click.testing import CliRunner
-from PySide6.QtCore import Qt
-from PySide6.QtWidgets import (
+from pytest import MonkeyPatch
+from pytestqt.qtbot import QtBot
+from qtpy.QtCore import Qt
+from qtpy.QtWidgets import (
     QApplication,
     QMessageBox,
 )
-from pytest import MonkeyPatch
-from pytestqt.qtbot import QtBot
 
 from manim_slides.config import Config, Key
 from manim_slides.defaults import CONFIG_PATH
-from manim_slides.wizard import KeyInput, Wizard, init, wizard
+from manim_slides.wizard import init, wizard
+from manim_slides.wizard.wizard import KeyInput, Wizard
 
 
 class TestKeyInput: