Bump Bazel version to 7.2.1

Release-Notes: skip
Change-Id: If5f59bb87a285675052f88859daebccc1585ed7c
diff --git a/.bazelversion b/.bazelversion
index 66ce77b..b26a34e 100644
--- a/.bazelversion
+++ b/.bazelversion
@@ -1 +1 @@
-7.0.0
+7.2.1