Build(deps): Bump onebox from 2.2.4 to 2.2.6 (#12219)

Bumps [onebox](https://github.com/discourse/onebox) from 2.2.4 to 2.2.6.
- [Release notes](https://github.com/discourse/onebox/releases)
- [Changelog](https://github.com/discourse/onebox/blob/master/CHANGELOG.md)
- [Commits](https://github.com/discourse/onebox/compare/v2.2.4...v2.2.6)

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile.lock

@@ -264,7 +264,7 @@ GEM
     omniauth-twitter (1.4.0)
       omniauth-oauth (~> 1.1)
       rack
-    onebox (2.2.4)
+    onebox (2.2.6)
       addressable (~> 2.7.0)
       htmlentities (~> 4.3)
       multi_json (~> 1.11)