Bump multi_json from 1.14.1 to 1.15.0 (#14400)

Bumps [multi_json](https://github.com/intridea/multi_json) from 1.14.1 to 1.15.0.
- [Release notes](https://github.com/intridea/multi_json/releases)
- [Changelog](https://github.com/intridea/multi_json/blob/master/CHANGELOG.md)
- [Commits](https://github.com/intridea/multi_json/compare/v1.14.1...v1.15.0)

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

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

Gemfile.lock

@@ -366,7 +366,7 @@ GEM
     mini_portile2 (2.4.0)
     minitest (5.14.1)
     msgpack (1.3.3)
-    multi_json (1.14.1)
+    multi_json (1.15.0)
     multipart-post (2.1.1)
     necromancer (0.5.1)
     net-ldap (0.16.2)