Bump parallel_tests from 3.3.0 to 3.4.0 (#15203)

Bumps [parallel_tests](https://github.com/grosser/parallel_tests) from 3.3.0 to 3.4.0.
- [Release notes](https://github.com/grosser/parallel_tests/releases)
- [Changelog](https://github.com/grosser/parallel_tests/blob/master/CHANGELOG.md)
- [Commits](https://github.com/grosser/parallel_tests/compare/v3.3.0...v3.4.0)

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

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

Gemfile

@@ -123,7 +123,7 @@ group :test do
   gem 'rspec-sidekiq', '~> 3.1'
   gem 'simplecov', '~> 0.19', require: false
   gem 'webmock', '~> 3.10'
-  gem 'parallel_tests', '~> 3.3'
+  gem 'parallel_tests', '~> 3.4'
   gem 'rspec_junit_formatter', '~> 0.4'
 end