Fix integrity failures.

tests/test-notebook/package.json

@@ -22,8 +22,8 @@
     "@jupyterlab/docregistry": "^0.16.2",
     "@jupyterlab/notebook": "^0.16.2",
     "@jupyterlab/observables": "^1.0.9",
-    "@jupyterlab/services": "^2.0.2",
     "@phosphor/algorithm": "^1.1.2",
+    "@phosphor/coreutils": "^1.3.0",
     "@phosphor/messaging": "^1.2.2",
     "@phosphor/widgets": "^1.5.0",
     "expect.js": "~0.3.1",