Bump bullet from 6.1.5 to 7.1.4 in /backend (#696)

Bumps [bullet](https://github.com/flyerhzm/bullet) from 6.1.5 to 7.1.4.
- [Changelog](https://github.com/flyerhzm/bullet/blob/main/CHANGELOG.md)
- [Commits](flyerhzm/bullet@6.1.5...7.1.4)

---
updated-dependencies:
- dependency-name: bullet
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

backend/Gemfile.lock

@@ -89,7 +89,7 @@ GEM
     bugsnag (6.26.0)
       concurrent-ruby (~> 1.0)
     builder (3.2.4)
-    bullet (6.1.5)
+    bullet (7.1.4)
       activesupport (>= 3.0.0)
       uniform_notifier (~> 1.11)
     byebug (11.1.3)
@@ -442,7 +442,7 @@ GEM
     tzinfo-data (1.2021.3)
       tzinfo (>= 1.0.0)
     unicode-display_width (2.4.2)
-    uniform_notifier (1.14.2)
+    uniform_notifier (1.16.0)
     vcr (6.2.0)
     warden (1.2.9)
       rack (>= 2.0.9)