fix(package): update apollo-server-express to version 2.9.15

Closes #6303

Author: greenkeeper[bot]

package.json

@@ -24,7 +24,7 @@
     "@parse/push-adapter": "3.2.0",
     "@parse/s3-files-adapter": "1.4.0",
     "@parse/simple-mailgun-adapter": "1.1.0",
-    "apollo-server-express": "2.9.14",
+    "apollo-server-express": "2.9.15",
     "bcryptjs": "2.4.3",
     "body-parser": "1.19.0",
     "commander": "4.0.1",