Updated checkout and setup-python actions in CI.

.github/workflows/main_ci.yml

@@ -11,11 +11,11 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
-      - name: Set up Python 3.8
-        uses: actions/setup-python@v1
+      - uses: actions/checkout@v4
+      - name: Set up Python 3.9
+        uses: actions/setup-python@v5
         with:
-          python-version: '3.8'
+          python-version: '3.9'
       - name: Linting
         run: |
           pip install pre-commit
@@ -27,12 +27,12 @@ jobs:
     strategy:
       max-parallel: 2
       matrix:
-        python-version: ['3.8', '3.9', '3.10']
+        python-version: ['3.8', '3.9', '3.10', '3.11']
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
 
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}