fix(deps): update dependency apollo-server to v2.25.4 [security]

Author: renovate[bot]

packages/voyager-server/package.json

@@ -24,7 +24,7 @@
     "@aerogear/voyager-conflicts": "0.9.0",
     "@aerogear/voyager-keycloak": "0.9.0",
     "@aerogear/voyager-tools": "0.9.0",
-    "apollo-server": "2.19.1",
+    "apollo-server": "2.25.4",
     "apollo-server-express": "2.19.1",
     "graphql-tools": "4.0.6"
   },