Update rxjs version

Author: jelbourn

package-lock.json

@@ -33,7 +33,7 @@
     "@angular/forms": ">=6.0.0-beta.7 <7.0.0",
     "@angular/platform-browser": ">=6.0.0-beta.7 <7.0.0",
     "core-js": "^2.4.1",
-    "rxjs": "^5.5.5",
+    "rxjs": "^5.5.7",
     "systemjs": "0.19.43",
     "tsickle": "^0.24.x",
     "tslib": "^1.7.1",