Update CI for MacOS.

Author: vsajip

.github/workflows/python-package.yml

@@ -30,8 +30,12 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        os: [ubuntu-latest, macos-12, macos-latest, windows-latest]
         python-version: ['3.7', '3.8', '3.9', '3.10', '3.11', '3.12', 'pypy-2.7', 'pypy-3.9']
+        exclude:
+          # macos-latest does not have Python 3.7
+          - os: macos-latest
+            python-version: '3.7'
 
     steps:
     - uses: actions/checkout@v3