Version bump, update changelog

Version bump, update changelog

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f1f989b..9077c39 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,13 @@
 All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/).
 
+## [0.40.0] - 2020-05-07
+### Fixed
+- Add missing attributes to `sync_sso`
+
+### Added
+- Add delete category method
+
 ## [0.39.3] - 2020-04-30
 ### Fixed
 - Add `reviewable_by_group_name` to categories
diff --git a/lib/discourse_api/version.rb b/lib/discourse_api/version.rb
index d4f40e1..7d70f04 100644
--- a/lib/discourse_api/version.rb
+++ b/lib/discourse_api/version.rb
@@ -1,4 +1,4 @@
 # frozen_string_literal: true
 module DiscourseApi
-  VERSION = "0.39.3"
+  VERSION = "0.40.0"
 end

GitHub sha: 97e9037a