use a fixed image version for the test stage

Author: phettberg

.github/workflows/workflow.yml

@@ -34,7 +34,7 @@ jobs:
         password: ${{ secrets.PYPI_API_TOKEN }}
 
   test:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     strategy:
       matrix:
         python-version: ['3.7', '3.8', '3.9', '3.10']
@@ -51,4 +51,4 @@ jobs:
         pip install -r requirements_dev.txt -e .
     - name: Test with pytest
       run: |
-        pytest -v
+        pytest -v