only use py 3.9 in CI

.github/workflows/docker-publish.yaml

@@ -23,15 +23,12 @@ env:
 jobs:
   lint:
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        python-version: [ "3.8", "3.9", "3.10" ]
     steps:
       - uses: actions/checkout@v3
-      - name: Set up Python ${{ matrix.python-version }}
+      - name: Set up Python 3.9
         uses: actions/setup-python@v3
         with:
-          python-version: ${{ matrix.python-version }}
+          python-version: "3.9"
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip