Update graphql to the latest version 🚀 (#6558)

* fix(package): update graphql to version 15.0.0

* chore(package): update lockfile package-lock.json

Co-authored-by: greenkeeper[bot] <23040076+greenkeeper[bot]@users.noreply.github.com>

Author: greenkeeper[bot]

package-lock.json

@@ -32,7 +32,7 @@
     "deepcopy": "2.0.0",
     "express": "4.17.1",
     "follow-redirects": "1.11.0",
-    "graphql": "14.6.0",
+    "graphql": "15.0.0",
     "graphql-list-fields": "2.0.2",
     "graphql-relay": "^0.6.0",
     "graphql-tools": "^4.0.7",