gh-pages: simplify

Author: mr-c

.github/workflows/gh-pages.yaml

@@ -25,22 +25,8 @@ jobs:
         uses: actions/setup-python@v4
         with:
           python-version: '3.9'
+          cache: pip
 
-      - name: Upgrade pip
-        run: |
-          # pip >= 20.1 so we can use ``pip cache dir``
-          python3 -m pip install --upgrade pip
-      - name: Get pip cache dir
-        id: pip-cache
-        run: echo "dir=$(pip cache dir)" >> "$GITHUB_OUTPUT"
-
-      - name: Cache dependencies
-        uses: actions/cache@v3
-        with:
-          path: ${{ steps.pip-cache.outputs.dir }}
-          key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt') }}
-          restore-keys: |
-            ${{ runner.os }}-pip-
       - name: Install dependencies
         run: python3 -m pip install -U -e ".[all]"