Update rails requirement from ~> 6.1.4 to >= 6.1.4, < 7.2.0

Updates the requirements on [rails](https://github.com/rails/rails) to permit the latest version.
- [Release notes](https://github.com/rails/rails/releases)
- [Commits](rails/rails@v6.1.4...v7.1.0)

---
updated-dependencies:
- dependency-name: rails
  dependency-type: direct:production
...

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

publify_core.gemspec

@@ -39,7 +39,7 @@ Gem::Specification.new do |s|
   # Force minimum nokogiri version to avoid security issues
   s.add_dependency "nokogiri", ">= 1.12.5"
   s.add_dependency "rack", ">= 2.2.3"
-  s.add_dependency "rails", "~> 6.1.4"
+  s.add_dependency "rails", ">= 6.1.4", "< 7.2.0"
   s.add_dependency "rails_autolink", "~> 1.1.0"
   s.add_dependency "rails-i18n", ">= 6.0", "< 7.1"
   s.add_dependency "rails-timeago", "~> 2.0"