fix: upgrade graphql from 15.4.0 to 15.6.0 (#1853)

Author: snyk-bot

package-lock.json

@@ -45,7 +45,7 @@
     "csurf": "1.11.0",
     "express": "4.17.1",
     "graphiql": "1.4.2",
-    "graphql": "15.4.0",
+    "graphql": "15.6.0",
     "history": "4.10.1",
     "immutable": "4.0.0-rc.9",
     "immutable-devtools": "0.1.5",