Update python in GHA to 3.9

Author: jakubno

.github/workflows/python_tests.yml

@@ -23,7 +23,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8'
+          python-version: '3.9'
 
       - name: Install and configure Poetry
         uses: snok/install-poetry@v1

.github/workflows/release.yml

@@ -266,7 +266,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
-          python-version: "3.8"
+          python-version: "3.9"
 
       - name: Install and configure Poetry
         uses: snok/install-poetry@v1

.github/workflows/release_candidates.yml

@@ -61,7 +61,7 @@ jobs:
         uses: actions/setup-python@v4
         if: ${{ contains( github.event.pull_request.labels.*.name, 'python-rc') }}
         with:
-          python-version: "3.8"
+          python-version: "3.9"
 
       - name: Install and configure Poetry
         uses: snok/install-poetry@v1