reset venv cache every month

Author: samuelgarcia

.github/workflows/full-test.yml

@@ -18,11 +18,17 @@ jobs:
       - uses: actions/checkout@v2
         with:
           python-version: 3.8
+      - name: Get current year-month
+        id: date
+        run: echo "::set-output name=date::$(date+'%Y-%m')"
       - uses: actions/cache@v2
+        # the cache for python package is reset:
+        #   * every month
+        #   * when requirements/requirements_testing change
         id: cache-venv
         with:
           path: ~/test_env
-          key: ${{ runner.os }}-venv-${{ hashFiles('**/requirements.txt') }}-${{ hashFiles('**/requirements_testing.txt') }}
+          key: ${{ runner.os }}-venv-${{ hashFiles('**/requirements.txt') }}-${{ hashFiles('**/requirements_testing.txt') }}-${{ steps.date.outputs.date }}
           restore-keys: |
             ${{ runner.os }}-venv-
       - name: Install dependencies