use ubuntu 22 for 3.7

Author: aphedges

.github/workflows/test-pr.yml

@@ -12,7 +12,7 @@ on:
 
 jobs:
   test:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04 # Needed for Python 3.7
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4