fix(ci): macOS CI failing with python{3.7, 3.8, 3.9}

Problem: macos-latest now points to M1 runners (macos-14-arm64) which do not
support python 3.7 - 3.9.

Solution: For these python versions, use the macos-12 (x86_64) runner.

Author: wookayin

.github/workflows/test.yml

@@ -32,9 +32,21 @@ jobs:
         exclude:
           - os: 'ubuntu-latest'
             python-version: '3.7'
+          - os: 'macos-latest'
+            python-version: '3.7'
+          - os: 'macos-latest'
+            python-version: '3.8'
+          - os: 'macos-latest'
+            python-version: '3.9'
         include:
           - os: 'ubuntu-20.04'
             python-version: '3.7'
+          - os: 'macos-12'
+            python-version: '3.7'
+          - os: 'macos-12'
+            python-version: '3.8'
+          - os: 'macos-12'
+            python-version: '3.9'
 
     name: "test (python ${{ matrix.python-version }}, ${{ matrix.os }})"
     runs-on: ${{ matrix.os }}