Update slim_lint requirement from ~> 0.31.0 to ~> 0.33.0

Updates the requirements on [slim_lint](https://github.com/sds/slim-lint) to permit the latest version.
- [Release notes](https://github.com/sds/slim-lint/releases)
- [Changelog](https://github.com/sds/slim-lint/blob/main/CHANGELOG.md)
- [Commits](sds/slim-lint@v0.31.0...v0.33.0)

---
updated-dependencies:
- dependency-name: slim_lint
  dependency-version: 0.33.0
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

govuk-components.gemspec

@@ -45,6 +45,6 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency("sass")
   spec.add_development_dependency("sassc", "~> 2.4.0")
   spec.add_development_dependency("slim", "~> 5.2.0")
-  spec.add_development_dependency("slim_lint", "~> 0.31.0")
+  spec.add_development_dependency("slim_lint", "~> 0.33.0")
   spec.add_development_dependency("webrick", "~> 1.9.0")
 end