Update rspec-rails requirement from ~> 6.1 to ~> 7.0 (#36)

Updates the requirements on [rspec-rails](https://github.com/rspec/rspec-rails) to permit the latest version.
- [Changelog](https://github.com/rspec/rspec-rails/blob/main/Changelog.md)
- [Commits](rspec/rspec-rails@v6.1.0...v7.0.0)

---
updated-dependencies:
- dependency-name: rspec-rails
  dependency-type: direct:development
...

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

paranoia_uniqueness_validator.gemspec

@@ -22,5 +22,5 @@ Gem::Specification.new do |gem|
 
   gem.add_development_dependency 'database_cleaner', '~> 2.0'
   gem.add_development_dependency 'paranoia', '~> 3.0'
-  gem.add_development_dependency 'rspec-rails', '~> 6.1'
+  gem.add_development_dependency 'rspec-rails', '~> 7.0'
 end