fix(deps): update dependency gcp-metadata to v3 (#757)

Author: renovate-bot

package.json

@@ -55,7 +55,7 @@
     "console-log-level": "^1.4.0",
     "extend": "^3.0.2",
     "findit2": "^2.2.3",
-    "gcp-metadata": "^2.0.0",
+    "gcp-metadata": "^3.0.0",
     "lodash.pickby": "^4.6.0",
     "p-limit": "^2.2.0",
     "semver": "^6.0.0",