Bump sentry-rails from 5.18.2 to 5.21.0 (#161)

Bumps [sentry-rails](https://github.com/getsentry/sentry-ruby) from 5.18.2 to 5.21.0.
- [Release notes](https://github.com/getsentry/sentry-ruby/releases)
- [Changelog](https://github.com/getsentry/sentry-ruby/blob/master/CHANGELOG.md)
- [Commits](getsentry/sentry-ruby@5.18.2...5.21.0)

---
updated-dependencies:
- dependency-name: sentry-rails
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Gemfile.lock

@@ -374,10 +374,10 @@ GEM
       rexml (~> 3.2, >= 3.2.5)
       rubyzip (>= 1.2.2, < 3.0)
       websocket (~> 1.0)
-    sentry-rails (5.18.2)
+    sentry-rails (5.21.0)
       railties (>= 5.0)
-      sentry-ruby (~> 5.18.2)
-    sentry-ruby (5.18.2)
+      sentry-ruby (~> 5.21.0)
+    sentry-ruby (5.21.0)
       bigdecimal
       concurrent-ruby (~> 1.0, >= 1.0.2)
     smart_properties (1.17.0)