Enable pip cache in CI (#413)

Author: bdraco

.github/workflows/python-package.yml

@@ -23,6 +23,7 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}
+          cache: "pip" # caching pip dependencies
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip