Update gemspec to include metadata (repository, changelog), and clean deprecated properties

[kpumuk]

Removed deprecated rubyforge_project property

  WARNING:  rubyforge_project= is deprecated and ignored. Please remove this from your gemspec to ensure that your gem continues to build in the future.
  WARNING:  See https://guides.rubygems.org/specification-reference/ for help

Added metadata fields, displayed on the RubyGems page. See https://rubygems.org/gems/activeadmin for example:

• source_code_uri
• changelog_uri
• bug_tracker_uri
• documentation_uri
• mailing_list_uri
• homepage_uri

https://guides.rubygems.org/specification-reference/

Build output

$ rake gem
ruby extconf.rb
checking for strlcpy() in string.h... yes
creating Makefile
make
linking shared-object thrift_native.so
gem build thrift.gemspec
WARNING:  open-ended dependency on bundler (>= 1.11, development) is not recommended
  if bundler is semantically versioned, use:
    add_development_dependency "bundler", "~> 1.11"
WARNING:  make sure you specify the oldest ruby version constraint (like ">= 3.0") that you want your gem to support by setting the `required_ruby_version` gemspec attribute
WARNING:  See https://guides.rubygems.org/specification-reference/ for help
  Successfully built RubyGem
  Name: thrift
  Version: 0.23.0
  File: thrift-0.23.0.gem

Ruby version warning will be addressed by https://github.com/apache/thrift/pull/3249

• [ ] Did you create an Apache Jira ticket? (Request account here, not required for trivial changes)
• [ ] If a ticket exists: Does your pull request title follow the pattern "THRIFT-NNNN: describe my issue"?
• [x] Did you squash your changes to a single commit? (not required, but preferred)
• [x] Did you do your best to avoid breaking changes? If one was needed, did you label the Jira ticket with "Breaking-Change"?
• [x] If your change does not involve any code, include [skip ci] anywhere in the commit message to free up build resources.