Cut v0.4.0 release (#16)

Author: jthomperoo

CHANGELOG.md

@@ -5,6 +5,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+## [0.4.0]
 - Add configurable `Issuer` field to override the `iss` claim in tokens and the OIDC discovery document
 
 ## [0.3.0]
@@ -19,7 +20,9 @@ Versioning](https://semver.org/spec/v2.0.0.html).
 - Initial release
 
 [Unreleased]:
-https://github.com/BusinessSimulations/dev-oidc-toolkit/compare/0.3.0...HEAD
+https://github.com/BusinessSimulations/dev-oidc-toolkit/compare/0.4.0...HEAD
+[0.4.0]:
+https://github.com/BusinessSimulations/dev-oidc-toolkit/compare/0.3.0...0.4.0
 [0.3.0]:
 https://github.com/BusinessSimulations/dev-oidc-toolkit/compare/0.2.0...0.3.0
 [0.2.0]: