[FEATURE] Add official support for Ruby 4.0 (#224)

This gems already works fine with Ruby 4, though, so let's make
it official.

https://github.com/ruby/ruby/releases/tag/v4.0.0

Author: oliverklee

.github/workflows/ci.yml

@@ -53,9 +53,12 @@ jobs:
           - { 'rails': '7.2', 'ruby': '3.2.8' }
           - { 'rails': '7.2', 'ruby': '3.3.10' }
           - { 'rails': '7.2', 'ruby': '3.4.8' }
+          - { 'rails': '7.2', 'ruby': '4.0.0' }
           - { 'rails': '8.0', 'ruby': '3.2.8' }
           - { 'rails': '8.0', 'ruby': '3.3.10' }
           - { 'rails': '8.0', 'ruby': '3.4.8' }
+          - { 'rails': '8.0', 'ruby': '4.0.0' }
           - { 'rails': '8.1', 'ruby': '3.2.8' }
           - { 'rails': '8.1', 'ruby': '3.3.10' }
           - { 'rails': '8.1', 'ruby': '3.4.8' }
+          - { 'rails': '8.1', 'ruby': '4.0.0' }

CHANGELOG.md

@@ -7,6 +7,8 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ### Added
 
+- Add support for Ruby 4.0 (#224)
+
 ### Changed
 
 ### Deprecated