[CI] Remove macos-12 build

See actions/runner-images#10721

Author: sbc100

.github/workflows/build_release.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-20.04, macos-12, macos-14, windows-latest]
+        os: [ubuntu-20.04, macos-14, windows-latest]
     defaults:
       run:
         shell: bash
@@ -33,7 +33,7 @@ jobs:
 
     - name: install ninja (osx)
       run: brew install ninja
-      if: matrix.os == 'macos-12' || matrix.os == 'macos-14'
+      if: matrix.os == 'macos-14'
 
     - name: install ninja (win)
       run: choco install ninja