fix(deps): update dependency graphql-tools to v2.18.0

Author: renovate-bot

package.json

@@ -18,7 +18,7 @@
     "cross-fetch": "1.1.1",
     "graphql": "0.12.3",
     "graphql-binding": "0.5.0",
-    "graphql-tools": "2.17.0"
+    "graphql-tools": "2.18.0"
   },
   "devDependencies": {
     "@types/graphql": "0.11.7",

yarn.lock

@@ -79,9 +79,9 @@ graphql-tools@2.16.0:
     graphql-subscriptions "^0.5.6"
     uuid "^3.1.0"
 
-graphql-tools@2.17.0:
-  version "2.17.0"
-  resolved "https://registry.yarnpkg.com/graphql-tools/-/graphql-tools-2.17.0.tgz#96c3cf54236a245b90e5adc4abdce81a2b37d1da"
+graphql-tools@2.18.0:
+  version "2.18.0"
+  resolved "https://registry.yarnpkg.com/graphql-tools/-/graphql-tools-2.18.0.tgz#8e2d6436f9adba1d579c1a1710ae95e7f5e7248b"
   dependencies:
     apollo-link "^1.0.0"
     apollo-utilities "^1.0.1"