Update dependency graphql-yoga to v1.9.1

Author: renovate-bot

basic/server/package.json

@@ -6,7 +6,7 @@
   },
   "dependencies": {
     "graphcool-binding": "1.3.5",
-    "graphql-yoga": "1.9.0"
+    "graphql-yoga": "1.9.1"
   },
   "devDependencies": {
     "now": "8.5.4"

basic/server/yarn.lock

@@ -575,9 +575,9 @@ graphql-tools@^2.23.1:
     iterall "^1.1.3"
     uuid "^3.1.0"
 
-graphql-yoga@1.9.0:
-  version "1.9.0"
-  resolved "https://registry.yarnpkg.com/graphql-yoga/-/graphql-yoga-1.9.0.tgz#d6854be9e5b1225430d52f90b95e62404da57c8c"
+graphql-yoga@1.9.1:
+  version "1.9.1"
+  resolved "https://registry.yarnpkg.com/graphql-yoga/-/graphql-yoga-1.9.1.tgz#1e83ac8d4c262cc28397f6b21acd7d894bcf1f4c"
   dependencies:
     "@types/cors" "^2.8.3"
     "@types/express" "^4.11.1"