Revert to testing on ubuntu-latest only

Author: matt-graham

.github/workflows/tests.yml

@@ -21,7 +21,7 @@ jobs:
     strategy:
       matrix:
         python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        os: [ubuntu-latest]
       fail-fast: false
 
     steps: