Bump oj from 3.6.11 to 3.6.12 (#8996)

Bumps [oj](https://github.com/ohler55/oj) from 3.6.11 to 3.6.12.
- [Release notes](https://github.com/ohler55/oj/releases)
- [Changelog](https://github.com/ohler55/oj/blob/master/CHANGELOG.md)
- [Commits](https://github.com/ohler55/oj/compare/v3.6.11...v3.6.12)

Signed-off-by: dependabot[bot] <support@dependabot.com>

Gemfile.lock

@@ -358,7 +358,7 @@ GEM
       concurrent-ruby (~> 1.0.0)
       sidekiq (>= 3.5.0)
       statsd-ruby (~> 1.2.0)
-    oj (3.6.11)
+    oj (3.6.12)
     omniauth (1.8.1)
       hashie (>= 3.4.6, < 3.6.0)
       rack (>= 1.6.2, < 3)