Remove version pin for Bazel 0.28.1.
FYI
# Please do not clear or delete this file when an incident is over.
# Instead, simply replace all values with empty strings ("").
---
-message: "Bazel 0.29.0 is broken with remote execution"
+message: "Bazel 0.29.0 might cause broken builds, but there's no workaround at the moment. We hope to have a patch release later today."
issue_url: "https://github.com/bazelbuild/bazel/issues/9284"
-last_good_bazel: "0.28.1"
+last_good_bazel: ""
