fix(deps): update dependency graphql-tools to v2.21.0

Author: renovate-bot

package.json

@@ -18,7 +18,7 @@
     "cross-fetch": "1.1.1",
     "graphql": "0.13.0",
     "graphql-binding": "1.2.0",
-    "graphql-tools": "2.20.2"
+    "graphql-tools": "2.21.0"
   },
   "devDependencies": {
     "@types/graphql": "0.12.3",

yarn.lock

@@ -86,13 +86,14 @@ graphql-tools@2.18.0:
     graphql-subscriptions "^0.5.6"
     uuid "^3.1.0"
 
-graphql-tools@2.20.2:
-  version "2.20.2"
-  resolved "https://registry.yarnpkg.com/graphql-tools/-/graphql-tools-2.20.2.tgz#b953ce7d62bbf6a1ca947101883ae725e1f58e02"
+graphql-tools@2.21.0:
+  version "2.21.0"
+  resolved "https://registry.yarnpkg.com/graphql-tools/-/graphql-tools-2.21.0.tgz#c0d0fbda6f40a87c8d267a2989ade2ae8b9a288e"
   dependencies:
-    apollo-link "^1.0.0"
+    apollo-link "^1.1.0"
     apollo-utilities "^1.0.1"
     deprecated-decorator "^0.1.6"
+    iterall "^1.1.3"
     uuid "^3.1.0"
 
 graphql@0.12.3: