Cache python installs (#621)

This pull request introduces support for caching Python installs in the
GitHub Action, allowing users to cache not only dependencies but also
the Python interpreter itself.

This works by setting the `UV_PYTHON_INSTALL_DIR` to a subdirectory of
the dependency cache path so that Python installs are directed there.

Fixes #135

---------

Co-authored-by: Kevin Stillhammer <[email protected]>

action.yml

@@ -56,6 +56,9 @@ inputs:
   prune-cache:
     description: "Prune cache before saving."
     default: "true"
+  cache-python:
+    description: "Upload managed Python installations to the Github Actions cache."
+    default: "false"
   ignore-nothing-to-cache:
     description: "Ignore when nothing is found to cache."
     default: "false"