Update dependency graphql to v15.4.0

Author: renovate-bot

package-lock.json

@@ -27,7 +27,7 @@
     "@types/node": "14.6.2",
     "apollo-datasource": "0.7.2",
     "apollo-server-micro": "2.19.1",
-    "graphql": "15.3.0",
+    "graphql": "15.4.0",
     "graphql-import": "1.0.2",
     "next": "10.0.5",
     "react": "16.13.1",