release: released CockroachDB version v25.4.0-alpha.0. Next version: v25.4.0-alpha.1

Release note: None
Epic: None
Release justification: non-production (release infra) change.

Author: cockroach-teamcity

pkg/build/version.txt

@@ -1 +1 @@
-v25.4.0-alpha.00000000
+v25.4.0-alpha.1