**Reason**:
Hasn't received any code since 2014 beside the routine maintenance.
Depends on semantic mediawiki as a composer package which breaks CI completely
- [ ] Archive documentation on `mediawiki.org` https://www.mediawiki.org/wiki/Extension:SemanticHighcharts
- [ ] Remove from `mediawiki/extensions` ( along with in `.gitmodules`)
- [x] Remove tests in `integration/config` ( `zuul/layout.yaml` )
- [ ] Remove from `translatewiki` ( `groups/MediaWiki/mediawiki-extensions.txt` )
- [ ] Remove manifest/other references from `mediawiki/vagrant` if they exist
- [ ] Empty repository and add a OBSOLETE file.
- [ ] Archive Phabricator project <#ProjectX> for associated extension/skin
- [ ] Edit Phabricator project <#ProjectX> description for associated extension/skin with a link to this ticket
- [ ] Archive the extension's diffusion repository: rESHI
- [ ] Mark the repository read-only in Gerrit: https://gerrit.wikimedia.org/r/#/admin/projects/mediawiki/extensions/SemanticHighcharts
- [ ] Delete the GitHub mirror: https://github.com/wikimedia/mediawiki-extensions-SemanticHighcharts