🔖 Prepare release 0.5.9

Signed-off-by: Peter Boling <peter.boling@gmail.com>

Author: pboling

CHANGELOG.md

@@ -13,6 +13,18 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Removed
 
+## [0.5.9] 2022-05-03
+### Added
+* Documentation related to Ruby compatibility
+* Updated CHANGELOG.md formatting
+* Corrected CHANGELOG.md typos
+* Hardened the CI build for the next few years(?!)
+* Require MFA to push new version to Rubygems
+* Replace Hash Rocket syntax with JSON-style symbols where possible
+* Project tooling in preparation for final release of 0.5.x series
+  - rubocop-ruby2_0
+  - overcommit
+
 ## [0.5.8] 2021-11-10
 ### Added
 * Added more documentation files to packaged gem, e.g. SECURITY.md, CODE_OF_CONDUCT.md
@@ -364,7 +376,8 @@ but please have a look at the unit tests.
 * Moved all non-Rails functionality from the Rails plugin:
   http://code.google.com/p/oauth-plugin/
 
-[Unreleased]: https://github.com/oauth-xx/oauth-ruby/compare/v0.5.8...v0.5-maintenance
+[Unreleased]: https://github.com/oauth-xx/oauth-ruby/compare/v0.5.9...v0.5-maintenance
+[0.5.9]: https://github.com/oauth-xx/oauth-ruby/releases/tag/v0.5.9
 [0.5.8]: https://github.com/oauth-xx/oauth-ruby/releases/tag/v0.5.8
 [0.5.7]: https://github.com/oauth-xx/oauth-ruby/releases/tag/v0.5.7
 [0.5.6]: https://github.com/oauth-xx/oauth-ruby/releases/tag/v0.5.6