First, version.txt will be stamped by Android CI with a release
candidate name like "ZV1A.240307.001".
Next, a genrule will read version.txt and embed the release candidate
name inside the Widevine CDM binary.
See also:
- go/wv-trunk "Versioning"
- cl/616721723
Bug: 327241925
Test: Coastguard
Change-Id: I892ee957c058ac5f624912a38a048781af5f3487
