ci: update and reduce the number of runners

Author: lengau

.github/workflows/tests.yaml

@@ -45,11 +45,9 @@ jobs:
   run-tests:
     strategy:
       matrix:
-        os: [macos-12, windows-2019, windows-2022]
-        python-version: [3.8, "3.10", "3.11"]
+        os: [macos-14-intel, windows-2022]
+        python-version: ["3.10"]
         include:
-          - os: ubuntu-20.04
-            python-version: "3.8"
           - os: ubuntu-22.04
             python-version: "3.10"