Bump node-fetch from 2.2.0 to 2.6.7

Bumps [node-fetch](https://github.com/node-fetch/node-fetch) from 2.2.0 to 2.6.7.
- [Release notes](https://github.com/node-fetch/node-fetch/releases)
- [Commits](node-fetch/node-fetch@v2.2.0...v2.6.7)

---
updated-dependencies:
- dependency-name: node-fetch
  dependency-type: direct:production
...

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

package.json

@@ -14,7 +14,7 @@
     "express": "^4.16.2",
     "firebase-admin": "6.0.0",
     "moment": "^2.22.2",
-    "node-fetch": "^2.2.0",
+    "node-fetch": "^2.6.7",
     "nodemon": "^1.18.3",
     "ws": "^6.0.0"
   },