fix(deps): update dependency apollo-server-express to v2.26.1

Author: renovate[bot]

packages/voyager-server/package.json

@@ -25,7 +25,7 @@
     "@aerogear/voyager-keycloak": "0.9.0",
     "@aerogear/voyager-tools": "0.9.0",
     "apollo-server": "2.19.1",
-    "apollo-server-express": "2.19.1",
+    "apollo-server-express": "2.26.1",
     "graphql-tools": "4.0.6"
   },
   "devDependencies": {