Bazel: Bump minimum supported version to 0.29.0

Change-Id: I069e56deb964624791bb0aa3ae095629adfe3bbb
Signed-off-by: David Ostrovsky <david@ostrovsky.org>

.bazelversion

@@ -1 +1 @@
-0.17.1
+0.29.0

WORKSPACE

@@ -11,7 +11,7 @@ http_archive(
 
 load("@bazel_skylib//:lib.bzl", "versions")
 
-versions.check(minimum_bazel_version = "0.17.1")
+versions.check(minimum_bazel_version = "0.29.0")
 
 load("//tools:bazlets.bzl", "load_bazlets")