Bump better_errors from 2.8.3 to 2.9.1 (#15117)

Bumps [better_errors](https://github.com/BetterErrors/better_errors) from 2.8.3 to 2.9.1.
- [Release notes](https://github.com/BetterErrors/better_errors/releases)
- [Commits](https://github.com/BetterErrors/better_errors/compare/v2.8.3...v2.9.1)

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

Gemfile

@@ -133,7 +133,7 @@ end
 group :development do
   gem 'active_record_query_trace', '~> 1.8'
   gem 'annotate', '~> 3.1'
-  gem 'better_errors', '~> 2.8'
+  gem 'better_errors', '~> 2.9'
   gem 'binding_of_caller', '~> 0.7'
   gem 'bullet', '~> 6.1'
   gem 'letter_opener', '~> 1.7'