Bump Bazel version to 3.0.0

Change-Id: I87857beb47dbc2c4a1a31db77ebd4598f3b88266
diff --git a/.bazelversion b/.bazelversion
index 7ec1d6d..4a36342 100644
--- a/.bazelversion
+++ b/.bazelversion
@@ -1 +1 @@
-2.1.0
+3.0.0