Add CHANGELOG entry for version updates

Author: chrisarcand

CHANGELOG.md

@@ -1,5 +1,20 @@
 # Vault Rails Changelog
 
+## Unreleased
+
+BREAKING CHANGES
+
+- Set minimum Ruby version to 3.2 (Ruby 3.1 reaches EOL March 31, 2025)
+- Set minimum Rails version to 7.0 (Rails 6.1 and earlier are EOL)
+
+IMPROVEMENTS
+
+- Restored Rails version matrix testing in CI (was accidentally dropped during CircleCI to GitHub Actions migration)
+- Updated CI to test currently supported Rails versions: 7.2, 8.0, 8.1
+- Updated CI to test Ruby versions: 3.2, 3.3, 3.4, 4.0
+- Updated CI to test currently supported Vault versions: 1.16.13 (LTS), 1.19.13 (LTS), 1.20.7, 1.21.2
+- Changed default Rails version in Gemfile from 6.0.0 to 7.2.0
+
 ## v0.11.0 (December 3, 2025)
 
 BREAKING CHANGES