Fix externs

Author: schmidt-sebastian

packages/firestore/externs.json

@@ -29,7 +29,7 @@
     "packages/util/dist/src/crypt.d.ts",
     "packages/util/dist/src/environment.d.ts",
     "packages/firestore/src/protos/firestore_bundle_proto.ts",
-    "packages/firestore/src/protos/firestore_proto_api.d.ts",
+    "packages/firestore/src/protos/firestore_proto_api.ts",
     "packages/firestore/src/util/error.ts",
     "packages/firestore/src/local/indexeddb_schema.ts",
     "packages/firestore/src/local/shared_client_state_schema.ts"