release: prepare analytics 3.3.0

[github-actions]

Release analytics 3.3.0

This PR prepares the analytics module for release.

Changes

• Bumps VERSION to 3.3.0 in lib/mixpanel-ruby/version.rb
• Updates CHANGELOG.md with a new section since the last v* tag
• Updates Readme.rdoc version header

After merging

1. Push tag v3.3.0 from the merge commit on master to trigger the publish workflow:

   git checkout master && git pull
   git tag v3.3.0
   git push origin v3.3.0
   

2. The publish workflow creates a draft GitHub release and publishes to RubyGems via OIDC trusted publishing. Review and publish the GitHub release after the workflow finishes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.16%. Comparing base (a125e26) to head (430e4d7).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #168   +/-   ##
=======================================
  Coverage   97.16%   97.16%           
=======================================
  Files          15       15           
  Lines         775      775           
=======================================
  Hits          753      753           
  Misses         22       22           

Flag	Coverage Δ
openfeature	100.00% <ø> (ø)

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