Be more frugal with workflow test matrix

Author: jg-rp

.github/workflows/tests.yaml

@@ -15,6 +15,18 @@ jobs:
             python-version: "3.8"
           - os: windows-latest
             python-version: "3.8"
+          - os: macos-latest
+            python-version: "3.9"
+          - os: windows-latest
+            python-version: "3.9"
+          - os: macos-latest
+            python-version: "3.10"
+          - os: windows-latest
+            python-version: "3.10"
+          - os: macos-latest
+            python-version: "3.11"
+          - os: windows-latest
+            python-version: "3.11"
     steps:
       - uses: actions/checkout@v3
         with: