fix(deps): update dependency apollo-server-express to v2.6.1

Author: renovate-bot

integration/graphql/package-lock.json

@@ -12,7 +12,7 @@
     "@nestjs/common": "6.2.4",
     "@nestjs/core": "6.2.4",
     "@nestjs/graphql": "6.2.1",
-    "apollo-server-express": "2.5.1",
+    "apollo-server-express": "2.6.1",
     "graphql": "14.3.1",
     "graphql-tools": "4.0.4",
     "reflect-metadata": "0.1.13",