Update actions/cache action to v3.0.4

Author: renovate-bot

.github/workflows/gh-page.yml

@@ -23,7 +23,7 @@ jobs:
           python-version: 3.6
 
       - name: Pip cache
-        uses: actions/[email protected].3
+        uses: actions/[email protected].4
         id: pip-cache
         with:
           path: ~/.cache/pip

.github/workflows/lint.yml

@@ -18,7 +18,7 @@ jobs:
         uses: actions/[email protected]
         with:
           python-version: ${{ matrix.python-version }}
-      - uses: actions/[email protected].3
+      - uses: actions/[email protected].4
         id: pip-cache
         with:
           path: ~/.cache/pip

.github/workflows/test.yml

@@ -57,7 +57,7 @@ jobs:
         python-version: ${{ matrix.python-version }}
 
     - name: Pip cache
-      uses: actions/[email protected].3
+      uses: actions/[email protected].4
       id: pip-cache
       with:
         path: ~/.cache/pip