Fix release for 0.9.1 version

Fix release for 0.9.1 version.

Review the complete diff at: master...release-0.9.1

• Checklist before merging:
  • Diff link is up-to-date and working.
  • The version has been adjusted according to SemVer.
  • Release notes are accurate.
  • Gitlab project has been updated and CI is passing.

This MR is generated by an automated release process. If you'd like to add additional information to the MR description, please do, but keep your changes to the area above the changelog, as that can be replaced by the automation process.

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0.9.1 Changelog

• Move development dependency from Gemfile to gemspec
• Deprecate ruby 2.x support in CI
• Add percent validation to add to 100
• Fix broken pipeline for release