Fix setuptools warning about av.filter package

Add explicit package discovery configuration to pyproject.toml to align
with setup.py's find_packages() call, preventing the "Package 'av.filter'
is absent from the packages configuration" warning during pip builds.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: WyattBlue

pyproject.toml

@@ -36,6 +36,9 @@ dynamic = ["version"]
 [tool.setuptools]
 zip-safe = false
 
+[tool.setuptools.packages.find]
+include = ["av*"]
+
 [tool.setuptools.dynamic]
 version = {attr = "av.about.__version__"}