Update rspec-its requirement from ~> 1.0 to ~> 2.0 (#526)

Updates the requirements on [rspec-its](https://github.com/rspec/rspec-its) to permit the latest version.
- [Changelog](https://github.com/rspec/rspec-its/blob/main/Changelog.md)
- [Commits](rspec/rspec-its@v1.0.0...v2.0.0)

---
updated-dependencies:
- dependency-name: rspec-its
  dependency-type: direct:production
...

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

Gemfile

@@ -6,7 +6,7 @@ gemspec
 
 gem 'rake' # For testing the Rake integration
 gem 'rspec', '~> 3.8'
-gem 'rspec-its', '~> 1.0'
+gem 'rspec-its', '~> 2.0'
 
 # For testing against multiple versions of Haml
 gem 'appraisal'