Bump @types/node-fetch from 2.1.5 to 2.1.6 in /functions (#49)

Bumps [@types/node-fetch](https://github.com/DefinitelyTyped/DefinitelyTyped) from 2.1.5 to 2.1.6.
- [Release notes](https://github.com/DefinitelyTyped/DefinitelyTyped/releases)
- [Commits](https://github.com/DefinitelyTyped/DefinitelyTyped/commits)

Signed-off-by: dependabot[bot] <support@dependabot.com>

functions/package.json

@@ -17,7 +17,7 @@
   },
   "main": "lib/index.js",
   "dependencies": {
-    "@types/node-fetch": "^2.1.5",
+    "@types/node-fetch": "^2.1.6",
     "actions-on-google": "^2.5.0",
     "firebase-admin": "^7.0.0",
     "firebase-functions": "^2.2.0",

functions/yarn.lock

@@ -291,10 +291,10 @@
   resolved "https://registry.yarnpkg.com/@types/mime/-/mime-2.0.0.tgz#5a7306e367c539b9f6543499de8dd519fac37a8b"
   integrity sha512-A2TAGbTFdBw9azHbpVd+/FkdW2T6msN1uct1O9bH3vTerEHKZhTXJUQXy+hNq1B0RagfU8U+KBdqiZpxjhOUQA==
 
-"@types/node-fetch@^2.1.5":
-  version "2.1.5"
-  resolved "https://registry.yarnpkg.com/@types/node-fetch/-/node-fetch-2.1.5.tgz#94f81fbb0cab2709a5275bbfab7ff93fd7d4bdc0"
-  integrity sha512-GuJUcxJt5VjAmkf23v5P2eBX6bVFp3ZVRFhuZhTLxAytlc8puxGDwdZAmQaV8l7A3mpm/xv14UjhSZIWt1UQAQ==
+"@types/node-fetch@^2.1.6":
+  version "2.1.6"
+  resolved "https://registry.yarnpkg.com/@types/node-fetch/-/node-fetch-2.1.6.tgz#4326288b49f352a142f03c63526ebce0f4c50877"
+  integrity sha512-Hv1jgh3pfpUEl2F2mqUd1AfLSk1YbUCeBJFaP36t7esAO617dErqdxWb5cdG2NfJGOofkmBW36fdx0dVewxDRg==
   dependencies:
     "@types/node" "*"