feat: add action to clean up stale caches

[axe312ger]

After a while, caches can grow.

We need to delete old ones.

Current workaround: find . -atime +30 -exec rm -f {} \; (delete all files in folder older as 30 days)

Note: The feature should somehow support to keep at least X caches, to ensure there is always a cache, even when the project was not worked on for a while)