update firebase-tools version (#3937)

Author: Feiyang1

packages/auth/package.json

@@ -25,7 +25,7 @@
     "@firebase/auth-types": "0.10.1"
   },
   "devDependencies": {
-    "firebase-tools": "8.11.2",
+    "firebase-tools": "8.12.1",
     "google-closure-compiler": "20200112.0.0",
     "google-closure-library": "20200224.0.0",
     "gulp": "4.0.2",