remove macos-12 from test matrix

The macos-12 platform has been removed from GitHub actions.

Author: Freax13

.github/workflows/build.yml

@@ -47,7 +47,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        platform: [ubuntu-latest, macos-12, macos-latest, windows-latest]
+        platform: [ubuntu-latest, macos-latest, windows-latest]
 
     runs-on: ${{ matrix.platform }}
     timeout-minutes: 15