fix(github-actions): tighten fileMatch (#14983)

* fix(github-actions): tighten fileMatch

* Update lib/modules/manager/github-actions/index.ts

lib/modules/manager/github-actions/index.ts

@@ -5,7 +5,7 @@ export { extractPackageFile } from './extract';
 
 export const defaultConfig = {
   fileMatch: [
-    '(^workflow-templates|\\.github\\/workflows)\\/[^/]+\\.ya?ml$',
+    '^(workflow-templates|\\.github\\/workflows)\\/[^/]+\\.ya?ml$',
     '(^|\\/)action\\.ya?ml$',
   ],
 };