Update changelog for 3.1.0 beta1 (#353)

Signed-off-by: James Hillyerd <james@hillyerd.com>

CHANGELOG.md

@@ -4,11 +4,21 @@ Change Log
 All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/).
 
-## [Unreleased]
+## [v3.1.0-beta1] - 2023-02-28
 
 ### Added
+- Monitor tab updates when messages are deleted (#337)
+- Initial framework for extensions
+- Initial Lua scripting implementation, supporting events:
+  - after.message_deleted
+  - after.message_stored
+  - before.mail_accepted
+- Provide `http` and `json` modules for Lua scripts
+
+### Fixed
 - Support for IP address as domain in RCPT TO (#285)
 
+
 ## [v3.0.4] - 2022-10-02
 
 ### Fixed
@@ -318,7 +328,8 @@ No change from beta1.
   specific message.
 
 
-[Unreleased]:   https://github.com/inbucket/inbucket/compare/v3.0.4...main
+[Unreleased]:   https://github.com/inbucket/inbucket/compare/v3.1.0-beta1...main
+[v3.1.0-beta1]: https://github.com/inbucket/inbucket/compare/v3.0.4...v3.1.0-beta1
 [v3.0.4]:       https://github.com/inbucket/inbucket/compare/v3.0.3...v3.0.4
 [v3.0.3]:       https://github.com/inbucket/inbucket/compare/v3.0.2...v3.0.3
 [v3.0.2]:       https://github.com/inbucket/inbucket/compare/v3.0.1-rc2...v3.0.2