Drop Python 3.7 and macos-12 from CI.

Author: vsajip

.github/workflows/tests.yml

@@ -32,12 +32,8 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-12, macos-latest, windows-latest]
-        python-version: ['3.7', '3.8', '3.9', '3.10', '3.11', '3.12', '3.13', 'pypy-3.9']
-        exclude:
-          # macos-latest does not have Python 3.7
-          - os: macos-latest
-            python-version: '3.7'
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        python-version: ['3.8', '3.9', '3.10', '3.11', '3.12', '3.13', 'pypy-3.9']
 
     steps:
     - uses: actions/checkout@v4
@@ -69,8 +65,6 @@ jobs:
         coverage run --branch test_pagesign.py
         coverage xml
     - name: Upload coverage to Codecov
-      # Repeated failures of Codecov on macos-12
-      # if: ${{ matrix.os != 'macos-12' }}
       uses: codecov/codecov-action@v4
       with:
         flags: unittests