Bump strong_migrations from 0.7.2 to 0.7.4 (#15389)

Bumps [strong_migrations](https://github.com/ankane/strong_migrations) from 0.7.2 to 0.7.4.
- [Release notes](https://github.com/ankane/strong_migrations/releases)
- [Changelog](https://github.com/ankane/strong_migrations/blob/master/CHANGELOG.md)
- [Commits](https://github.com/ankane/strong_migrations/compare/v0.7.2...v0.7.4)

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

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

Gemfile.lock

@@ -609,7 +609,7 @@ GEM
     stoplight (2.2.1)
     streamio-ffmpeg (3.0.2)
       multi_json (~> 1.8)
-    strong_migrations (0.7.2)
+    strong_migrations (0.7.4)
       activerecord (>= 5)
     temple (0.8.2)
     terminal-table (1.8.0)