Update rubocop-govuk requirement from = 5.0.2 to = 5.0.3

Updates the requirements on [rubocop-govuk](https://github.com/alphagov/rubocop-govuk) to permit the latest version.
- [Changelog](https://github.com/alphagov/rubocop-govuk/blob/main/CHANGELOG.md)
- [Commits](alphagov/rubocop-govuk@v5.0.2...v5.0.3)

---
updated-dependencies:
- dependency-name: rubocop-govuk
  dependency-type: direct:development
...

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

govuk_schemas.gemspec

@@ -26,7 +26,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "pry-byebug"
   spec.add_development_dependency "rake", "~> 13.0"
   spec.add_development_dependency "rspec", "~> 3.4"
-  spec.add_development_dependency "rubocop-govuk", "5.0.2"
+  spec.add_development_dependency "rubocop-govuk", "5.0.3"
 
   spec.required_ruby_version = ">= 3.1.4"
 end