Build(deps): Bump diffy from 3.3.0 to 3.4.0

Bumps [diffy](https://github.com/samg/diffy) from 3.3.0 to 3.4.0.
- [Release notes](https://github.com/samg/diffy/releases)
- [Changelog](https://github.com/samg/diffy/blob/main/CHANGELOG)
- [Commits](https://github.com/samg/diffy/compare/3.3.0...3.4.0)

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

Gemfile.lock

@@ -97,7 +97,7 @@ GEM
       addressable
     debug_inspector (0.0.3)
     diff-lcs (1.4.4)
-    diffy (3.3.0)
+    diffy (3.4.0)
     discourse-ember-source (3.12.2.2)
     discourse_image_optim (0.26.2)
       exifr (~> 1.2, >= 1.2.2)