Update Sphinx to 9.1.0, RTD theme to 3.1.0, Pillow to >=12.2.0

Also patch pyglet LibraryMock to add __bool__/__iter__ so doc builds
don't crash when ffmpeg codec init runs under sys.is_pyglet_doc_run.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Paul V Craven

doc/conf.py

@@ -52,6 +52,13 @@
 # 2. The commit: https://github.com/pyglet/pyglet/commit/97076c3a33a7d368cc9c9e44ca67769b6a16a905
 sys.is_pyglet_doc_run = True
 
+# pyglet 3.0.dev3 LibraryMock lacks __iter__/__bool__, causing crashes
+# when ffmpeg codec init calls get_input_extensions() during doc builds.
+# Patch before any pyglet imports trigger media codec loading.
+import pyglet.lib  # noqa: E402
+pyglet.lib.LibraryMock.__bool__ = lambda self: False
+pyglet.lib.LibraryMock.__iter__ = lambda self: iter([])
+
 # --- Pre-processing Tasks
 
 # Report our diagnostic info

pyproject.toml

@@ -20,7 +20,7 @@ classifiers = [
     "Topic :: Software Development :: Libraries :: Python Modules",
 ]
 dependencies = [
-    "pillow>=11.3.0",
+    "pillow>=12.2.0",
     "pytiled-parser~=2.2.9",
     "pyglet==3.0.dev3",
 ]
@@ -40,8 +40,8 @@ extras = [
 ]
 # Used for dev work
 dev = [
-    "sphinx==8.1.3",               # April 2024 | Updated 2024-07-15, 7.4+ is broken with sphinx-autobuild
-    "sphinx_rtd_theme==3.0.2",     # Nov 2024
+    "sphinx==9.1.0",               # April 2026
+    "sphinx_rtd_theme==3.1.0",     # April 2026
     "sphinx-rtd-dark-mode==1.3.0",
     "sphinx-autobuild==2024.10.3", # April 2024 | Due to this, Python 3.10+ is required to serve docs
     "sphinx-copybutton==0.5.2",    # April 2023