www/ruby-rack-contrib: update to 2.3.0

2.3.0 (2020-11-30)

The list of changes in this release is long, and should serve as a warning
to me to make releases more often, as it cuts down on typing.  Thanks to
everyone who made PRs, checked PRs, merged PRs, and... renewed PRs.
Special thanks to Andrew Konchin (@andrykonchin) who is responsible for
over half the changes in this monster release, and who has come on board
as a maintainer.

This release removes the Rack::Runtime and Rack::Config middleware.
This may seem like a foolhardy thing to do in a minor release, but rack
itself ships with functionally identical versions.  Compatibility has been
maintained by having require "rack/contrib/<thing>" still work, but that
should be changed to require "rack/<thing>" instead.

* A #close method was added to the body that is returned by Rack::Signals.
* A stub CHANGELOG.md, pointing to the canonical source of release notes,
  has been added.
* Thread safety issues in Rack::Access, Rack::CommonCookies, and
  Rack::Deflect have been fixed. Additionally, the need for a thread-safe
  external cache object in Rack::LazyConditionalGet has been documented.
* A SPEC violation in Rack::CSSHTTPRequest has been fixed.
* Case-sensitive header problems in a whole bunch of middlewares have been
  fixed.
* Rack::JSONBodyParser now only rescues JSON::ParserError if it is raised
  within the middleware's own code. Exceptions raised by the application
  itself will now be left alone to be handled elsewhere.
* All string literals are now frozen.
* Residual ye olde Ruby compatibility checks were removed from
  Rack::Backstage, Rack::MailExceptions and Rack::NestedParams.
* The length calculation in Rack::JSONP has been made simpler.


(taca)