chore(deps): update dependency @types/graphql to v0.12.2

Author: renovate-bot

package.json

@@ -27,7 +27,7 @@
     "graphql-tools": "^2.14.0"
   },
   "devDependencies": {
-    "@types/graphql": "0.11.7",
+    "@types/graphql": "0.12.2",
     "@types/node": "8.5.2",
     "typescript": "2.6.2"
   }