chore(deps): update dependency concat-stream to v2 (#244)

Author: renovate[bot]

packages/google-cloud-compute/package.json

@@ -50,7 +50,7 @@
   "devDependencies": {
     "@google-cloud/nodejs-repo-tools": "^3.0.0",
     "codecov": "^3.0.2",
-    "concat-stream": "^1.6.2",
+    "concat-stream": "^2.0.0",
     "eslint": "^5.0.0",
     "eslint-config-prettier": "^3.0.0",
     "eslint-plugin-node": "^8.0.0",