v1.17.2

This is a security/bug fix patch release. It should be safe to update for
everyone.

• Updated dependencies

  • nerves_system_br v1.17.1
  • Buildroot 2021.08.1
  • Erlang/OTP 24.1.2

• Improvements

  • Include software versioning and licensing info (see legal-info directory in
    artifact)