Bump Bazel version to 4.2.0

Change-Id: I9c2faeab5f897579fa445b870641bf113dbf66a8
diff --git a/.bazelversion b/.bazelversion
index 7c69a55..6aba2b2 100644
--- a/.bazelversion
+++ b/.bazelversion
@@ -1 +1 @@
-3.7.0
+4.2.0