build: narrow down prettier file set

Fixes that the formatting check was catching some files incorrectly, like pnpm lock file.

.ng-dev/format.mts

@@ -6,5 +6,7 @@ import {FormatConfig} from '@angular/ng-dev';
  */
 export const format: FormatConfig = {
   buildifier: true,
-  prettier: true,
+  prettier: {
+    matchers: ['**/*.{js,ts,mts,mjs,json}', '!.yarn/**'],
+  },
 };