Update cache to v4

Author: shengy90

.github/workflows/lint_and_test.yaml

@@ -13,7 +13,7 @@ jobs:
           python-version: "3.11"
       - run: pip install pipenv
       - name: Cache virtualenvs
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: ~/.local/share/virtualenvs/
           key: ${{ runner.os }}-python-${{ steps.setup-python.outputs.python-version }}-pipenv-${{ hashFiles('Pipfile.lock') }}