Bump Bazel version to 3.0.0

Change-Id: I33fd108769b5dc5212792ad144bfff4c9d77b461
diff --git a/.bazelversion b/.bazelversion
index ccbccc3..4a36342 100644
--- a/.bazelversion
+++ b/.bazelversion
@@ -1 +1 @@
-2.2.0
+3.0.0