CI: use setup-python's built in pip dependency caching

Simplify the workflow by specifying caching though setup-python's
with-arguments.

Signed-off-by: Joshua Lock <[email protected]>

.github/workflows/ci.yml

@@ -41,20 +41,8 @@ jobs:
         uses: actions/setup-python@13ae5bb136fac2878aff31522b9efb785519f984
         with:
           python-version: ${{ matrix.python-version }}
-
-      - name: Find pip cache dir
-        id: pip-cache
-        run: echo "dir=$(pip cache dir)" >> $GITHUB_OUTPUT
-
-      - name: pip cache
-        uses: actions/cache@9b0c1fce7a93df8e3bb8926b0d6e9d89e92f20a7
-        with:
-          # Use the os dependent pip cache directory found above
-          path: ${{ steps.pip-cache.outputs.dir }}
-          # A match with 'key' counts as cache hit
-          key: ${{ runner.os }}-pip-${{ hashFiles('requirements*.txt') }}
-          # A match with 'restore-keys' is used as fallback
-          restore-keys: ${{ runner.os }}-pip-
+          cache: "pip"
+          cache-dependency-path: "requirements*.txt"
 
       - name: Install dependencies
         run: |