CI: use macos-13 for Ruby 2.4, 2.5

Author: olleolleolle

.github/workflows/test.yml

@@ -15,6 +15,13 @@ jobs:
       matrix:
         ruby: ${{ fromJson(needs.ruby-versions.outputs.versions) }}
         os: [ ubuntu-latest, macos-latest ]
+        exclude:
+          - { os: macos-latest, ruby: '2.4' }
+          - { os: macos-latest, ruby: '2.5' }
+        include:
+          - { os: macos-13, ruby: '2.4' }
+          - { os: macos-13, ruby: '2.5' }
+
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v4