fix: apply prettier formatting to headers-xcframework-test

Pre-existing formatting lint failure from #57442 that surfaces on this
branch after merging main. Format-only change, no behavior change.

Author: intergalacticspacehighway

packages/react-native/scripts/ios-prebuild/__tests__/headers-xcframework-test.js

@@ -20,7 +20,7 @@ const os = require('os');
 const path = require('path');
 
 describe('buildDepsHeadersXcframework set-equality gate', () => {
-  let tmp /*: string */;
+  let tmp; /*: string */
   beforeEach(() => {
     tmp = fs.mkdtempSync(path.join(os.tmpdir(), 'deps-headers-test-'));
   });