remove macos-12 from CI test matrix

macos-12 has been removed from GitHub actions.

Author: Freax13

.github/workflows/ci.yml

@@ -36,7 +36,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-12, windows-latest, macos-latest]
+        os: [ubuntu-latest, windows-latest, macos-latest]
     runs-on: ${{ matrix.os }}
     timeout-minutes: 30