[oss-timeseries] fix missed app_routing/ dep needed for sync (#4179)
[oss-timeseries] fix missed app_routing/ dep needed for sync (#4179)

PR [1] introduced a sync-breaking change, due to app_routing/
having a transitive dependency that it did not depend on
explicitly. This change fixes the strict dep.

The test sync cl/332324994 from PR [1] actually failed.

Googlers, see the newer test sync cl/332491049, which should
actually work this time.

[1] https://github.com/tensorflow/tensorboard/pull/4173
tensorflow/tensorboard,tensorflow/tensorboard,tensorflow/tensorboard,tensorflow/tensorboard,tensorflow/tensorboard,tensorflow/tensorboard,tensorflow/tensorboard