chore: combine duplicate Ruby 4.0 release notes

Author: yoshi-automation

grafeas/CHANGELOG.md

@@ -4,17 +4,12 @@
 
 #### Features
 
-* Update minimum Ruby to v3.2 and required dependencies for Ruby v4.0 ([#32849](https://github.com/googleapis/google-cloud-ruby/issues/32849)) 
-* Update minimum Ruby to v3.2 and required dependencies for Ruby v4.0 ([#32851](https://github.com/googleapis/google-cloud-ruby/issues/32851)) 
-* Update minimum Ruby to v3.2 and required dependencies for Ruby v4.0 ([#32853](https://github.com/googleapis/google-cloud-ruby/issues/32853)) 
-* Update minimum Ruby to v3.2 and required dependencies for Ruby v4.0 ([#32854](https://github.com/googleapis/google-cloud-ruby/issues/32854)) 
-* Update minimum Ruby to v3.2 and required dependencies for Ruby v4.0 ([#32855](https://github.com/googleapis/google-cloud-ruby/issues/32855)) 
+* Upgrade dependencies for Ruby v4.0 and drop Ruby v3.1 support
 
 ### 1.6.0 (2026-03-18)
 
 #### Features
 
-* Update minimum Ruby to v3.2 and required dependencies for Ruby v4.0 ([#32871](https://github.com/googleapis/google-cloud-ruby/issues/32871)) 
 
 ### 1.5.3 (2025-09-12)