.github/workflows/codeql-analysis.yml: Add PIP caching

Adds caching of PIP dependencies. This reduces overall execution time
and decreases likelihood of a network error reaching out pypi to get
the dependencies.

Caching happens based on modules specified in pip-requirements.txt.

Cc: Sean Brogan <sean.brogan@microsoft.com>
Cc: Michael Kubacki <mikuback@linux.microsoft.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>