Run tests regularly

.github/workflows/tests.yml

@@ -5,6 +5,8 @@ on:
     branches:
       - main
   pull_request:
+  schedule:
+    - cron: "37 1 1 * *"
 
 jobs:
   tests:
@@ -14,7 +16,6 @@ jobs:
       fail-fast: false
       matrix:
         python-version:
-          - "3.8"
           - "3.9"
           - "3.10"
           - "3.11"
@@ -26,6 +27,7 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}
+          cache: pip
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip tox