[build] Use `macos-12` image for `yt-dlp_macos` (#10063)

Ref: https://github.blog/changelog/2024-05-20-actions-upcoming-changes-to-github-hosted-macos-runners/

Authored by: bashonly

.github/workflows/build.yml

@@ -237,7 +237,7 @@ jobs:
   macos:
     needs: process
     if: inputs.macos
-    runs-on: macos-11
+    runs-on: macos-12
 
     steps:
       - uses: actions/checkout@v4