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_slide.py

@@ -2,6 +2,7 @@ import random
 import shutil
 from pathlib import Path
 
+import numpy as np
 import pytest
 from click.testing import CliRunner
 from manim import (
@@ -17,6 +18,7 @@ from manim import (
     GrowFromCenter,
     Text,
 )
+from packaging import version
 from pydantic import ValidationError
 
 from manim_slides.config import PresentationConfig
@@ -29,7 +31,13 @@ from manim_slides.slide.manim import Slide
     "renderer",
     [
         "--CE",
-        "--GL",
+        pytest.param(
+            "--GL",
+            marks=pytest.mark.skipif(
+                version.parse(np.__version__) >= version.parse("1.25"),
+                reason="ManimGL requires numpy<1.25, which is outdate",
+            ),
+        ),
     ],
 )
 def test_render_basic_slide(