[DRE-maint] Bug#995354: Requires to package ruby-thread-local

[Kentaro Hayashi]

At least, updating to async-http 0.56.0 or later will satisfy dependency.

  https://rubygems.org/gems/async-http/versions/0.56.0

async-http 0.56.0 or later requires protocol-http >= 0.22.0 < 0.23,
but ruby-protocol-http 0.22.5-1 is packaged in sid.

It also adds new development dependency for localhost,
but ruby-localhost is already packaged in sid.