Set .bazelversion to 6.2.1

Change-Id: I7eb0e210131f21f88c0c1d5810a18c86ce95bfe8

.bazelversion

diff --git a/.bazelversion b/.bazelversion
index ac14c3d..024b066 100644
--- a/.bazelversion
+++ b/.bazelversion
@@ -1 +1 @@
-5.1.1
+6.2.1