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)
- 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 (no project)
- Edit Phabricator project <#ProjectX> description for associated extension/skin with a link to this ticket (no project)
- 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