Fix CI python version as 3.8 is no longer available in GH actions

.github/workflows/continuous_integration.yml

@@ -6,13 +6,14 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repo
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
+
       - name: Setup Python
-        uses: actions/setup-python@v1
-        with:
-          python-version: 3.8
+        uses: actions/setup-python@v5
+
       - name: Install pipenv
         run: pip install pipenv
+
       - name: Check code formatting
         run: |
           pipenv install pre_commit
@@ -26,27 +27,29 @@ jobs:
       QGIS_TEST_VERSION: ${{ matrix.qgis_version }}
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           submodules: recursive
+
       - name: Run tests
         run: |
           docker compose -f .docker/docker-compose.yml run qgis /usr/src/.docker/run-docker-tests.sh
   test_packaging:
       runs-on: ubuntu-latest
       steps:
         - name: Checkout
-          uses: actions/checkout@v3
+          uses: actions/checkout@v4
           with:
             submodules: recursive
+
         - name: Setup Python
-          uses: actions/setup-python@v4
-          with:
-            python-version: 3.8
-            cache: 'pip'
+          uses: actions/setup-python@v5
+
         - name: Install toolchain
           run: pip install build
+
         - name: Package with build
           run:  python -m build
+
         - name: Install with pip
           run: pip install .