Pin Bazel / MacOS to 0.13.0 for now
Pin Bazel / MacOS to 0.13.0 for now

Bazel 0.14.1 isn't on brew as a binary package yet, and compiling from
source takes longer than Travis is willing to wait.

ulfjack/ryu,ulfjack/ryu,ulfjack/ryu,ulfjack/ryu