Minor, bump in hpack version
- Regenerate golden files for the bump in hpack's version:
---- This file has been generated from package.yaml by hpack version 0.31.0.
++-- This file has been generated from package.yaml by hpack version 0.31.1.
---- This file has been generated from package.yaml by hpack version 0.31.0.
++-- This file has been generated from package.yaml by hpack version 0.31.1.