[ Merge of http://go/wvgerrit/83629 ]
In a previous change, the `VersionNumberChangeCanary` test started
to fail when Android changed their version number from "10" to "R".
I forgot to also change the Widevine CMD version string from "15.0.0"
to "16.0.0".
Test: Run `request_license_test` on Android
Bug: 137784842
Change-Id: I157aa6ac518423911e806b1278d723a86579c8cd