macos-latest to macos-12

Author: ota-meshi

.github/workflows/CI.yml

@@ -39,7 +39,7 @@ jobs:
             os: windows-latest
           - eslint: 7
             node: 16
-            os: macos-latest
+            os: macos-12
           # On old Node.js versions
           - eslint: 7
             node: 14