build(deps): only use python-apt-wheels repo for python-apt (#659)

This fixes the fact that uv was checking the python-apt-wheels repository for all wheels, when in fact we only want it to check that repository for python-apt.

Author: lengau

pyproject.toml

@@ -370,3 +370,7 @@ conflicts = [
 [[tool.uv.index]]
 name = "python-apt-wheels"
 url = "https://people.canonical.com/~lengau/python-apt-ubuntu-wheels/"  # workaround to get python-apt to install across multiple platforms
+explicit = true
+
+[tool.uv.sources]
+python-apt = { index = "python-apt-wheels" }