PYTHON-5131 Migrate off of Ubuntu 20.04 GitHub Actions Runners (#616)

Author: blink1073

.github/workflows/tests.yml

@@ -26,7 +26,7 @@ jobs:
       matrix:
         os:
           - "ubuntu-latest"
-          - "ubuntu-20.04"
+          - "ubuntu-22.04"
           - "windows-latest"
           - "macos-latest"
         mongodb-version: