vcs: revert "ci: bump macOS runner to macos-12 to fix homebrew error"

This reverts commit 9ed74bd.

Author: larpon

.github/workflows/ci.yml

@@ -78,7 +78,7 @@ jobs:
           test "${SDL2_VERSION}" = "$VER" || exit 1
 
   macos:
-    runs-on: macos-12
+    runs-on: macos-11
     timeout-minutes: 30
     env:
       SDL2_VERSION: 2.30.0