fix: match grpc version to gax (#141)

Author: igorbernstein2

package.json

@@ -32,7 +32,7 @@
     "node": ">=8"
   },
   "dependencies": {
-    "@grpc/grpc-js": "^1.1.1"
+    "@grpc/grpc-js": "~1.5.0"
   },
   "devDependencies": {
     "@grpc/proto-loader": "^0.6.2",