try yet again

.github/workflows/ci.yml

@@ -5,12 +5,17 @@ on: [push, pull_request]
 jobs:
   build:
 
+    if: ${{ matrix.os == 'macos' && matrix.python-minor-version < 10 }}:
+    runs-on: 'macos-13'
+    if: ${{ matrix.os == 'macos' && matrix.python-minor-version >= 10 }}:
+    runs-on: 'macos-latest'
+    if: ${{ matrix.os != 'macos' }}:
     runs-on: ${{ matrix.os }}
 
     strategy:
       matrix:
-        os: [ 'macos-latest', 'ubuntu-latest', 'windows-latest' ]
-        python-version: [ '3.7', '3.8', '3.9', '3.10', '3.11', '3.12' ]
+        os: [ 'macos', 'ubuntu-latest', 'windows-latest' ]
+        python-minor-version: [ 7, 8, 9, 10, 11, 12 ]
 
     steps:
     - uses: actions/checkout@v4
@@ -19,7 +24,7 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v5
       with:
-        python-version: ${{ matrix.python-version }}
+        python-version: '3.${{ matrix.python-minor-version }}'
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
@@ -30,7 +35,7 @@ jobs:
       if: matrix.os == 'windows-latest'
       run: pytest
     - name: Run typechecking with mypy and unit tests with pytest (skip coverage)
-      if: matrix.os == 'macos-latest'
+      if: matrix.os == 'macos'
       run: |
         make typecheck
         pytest