test: Initialize gax stream (#1368)

* Initialize gax stream

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* Keep the type on this variable

* Downgrade promisify

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: danieljbruce

package.json

@@ -41,7 +41,7 @@
     "precompile": "gts clean"
   },
   "dependencies": {
-    "@google-cloud/promisify": "^4.0.0",
+    "@google-cloud/promisify": "4.0.0",
     "arrify": "^2.0.1",
     "async-mutex": "^0.5.0",
     "concat-stream": "^2.0.0",

protos/protos.d.ts

@@ -1886,7 +1886,7 @@ describe('Request', () => {
   });
 
   describe('requestStream_', () => {
-    let GAX_STREAM: gax.CancellableStream;
+    let GAX_STREAM: gax.CancellableStream = {} as gax.CancellableStream;
     const CONFIG = {};
 
     beforeEach(() => {