Ruby Gemini AI 3.1.1

New version available on RubyGems:

gem 'gemini-ai', '~> 3.1', '>= 3.1.1'

New in this version:

• Fixing an issue that caused errors in streaming when Google returns blockReason SAFETY:
  • check candidates existance #9 (thanks @naoa).
• Increasing compatibility with other gems:
  • Lower googleauth gem version requirement #10 (thanks @niciliketo)
• making server_sent_events: optional e8ca529