Downgrade MacOS CI runners

The current macos-latest tag points to macos-14, running on arm64. We
currently can't support this architecture as it does not support
Python3.7

Author: AlexanderWells-diamond

.github/workflows/code.yml

@@ -53,7 +53,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, windows-latest, macos-latest]
+        os: [ubuntu-latest, windows-latest, macos-13]
         python: [cp37, cp38, cp39, cp310]
 
         include: