helpers.ts: for (const key in docs) -> for (const key of Object.keys(docs)) to fix the lint error: https://eslint.org/docs/latest/rules/guard-for-in

Author: dconeybe

packages/firestore/test/integration/util/helpers.ts

@@ -322,7 +322,7 @@ export function withTestCollectionSettings<T>(
       let writeBatch_: WriteBatch | null = null;
       let writeBatchSize = 0;
 
-      for (const key in docs) {
+      for (const key of Object.keys(docs)) {
         if (writeBatch_ === null) {
           writeBatch_ = writeBatch(setupDb);
         }