ci: use setup python instead of conda

.github/workflows/test.yml

@@ -15,10 +15,11 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - name: Set up Conda
-        uses: conda-incubator/setup-miniconda@v2
+      - name: Set up Python
+        uses: actions/setup-python@v4
         with:
           python-version: "3.8"
+          cache: "pip"
       - name: Install dependencies and package
         run: pip install -e . mypy
       - name: Minimal test, --help should work