❓ 🔧 ci: Speed up ansible-lint builds with static key

This commit changes the key used for the Python pip caching. Previously, it used the commit hash to determine whether to retrieve a cache or not. While this works for the main branch more often than not, it does make Pull Requests run a lot longer because the job has to install ansible fully.

The desired behavior I want is for the pip cache to be refreshed when a new image is pulled from Docker Hub. Since I don't need Ansible to keep up with the latest, hottest changes, it is OK if the version is not refreshed all the time. I will keep up with changes as they are shipped to the python:slim container images.