On Rubygems.org

$ git tag -a vx.x.x
$ git push --follow-tags
$ gem push pixelchart-x.x.x.gem

See https://guides.rubygems.org/publishing/.

On new release don't forget to rebuild the library documentation:

$ bundle exec yard doc

On AUR

$ updpkgsums
$ makepkg --printsrcinfo > .SRCINFO