Use macOS 13 on CI

"macos-latest" is currently macOS 12. Using macOS 13 may be faster.

Author: EliahKagan

.github/workflows/pythonpackage.yml

@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: ["ubuntu-latest", "macos-latest", "windows-latest"]
+        os: ["ubuntu-latest", "macos-13", "windows-latest"]
         python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12"]
         include:
         - experimental: false