ci: enable py37 testing

Author: aviau

.github/workflows/tests.yml

@@ -2,9 +2,10 @@ name: Tests
 on: push
 jobs:
   tests:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
     strategy:
       matrix:
+        os: ['ubuntu-latest']
         python-version: [
           '3.8',
           '3.9',
@@ -13,7 +14,10 @@ jobs:
           '3.12',
         ]
         include:
+          - python-version: '3.7'
+            os: 'ubuntu-22.04'
           - python-version: '3.9'
+            os: 'ubuntu-latest'
             post-venv: 'venv/bin/pip install "urllib3<2" "requests<=2.30" "types-requests<=2.30"'
     name: Python ${{ matrix.python-version }} ${{ matrix.post-venv }}
     steps: