Update changelog to include PR 1215

Author: Sephster

CHANGELOG.md

@@ -9,6 +9,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - The server will now validate redirect uris according to rfc8252 (PR #1203)
 - Events emitted now include the refresh token and access token payloads (PR #1211)
 
+### Changed
+- Keys are now validated using `openssl_pkey_get_private()` and openssl_pkey_get_public()` instead of regex matching (PR #1215)
+
 ### Fixed
 - The server will now only recognise and handle an authorization header if the value of the header is non-empty. This is to circumvent issues where some common frameworks set this header even if no value is present (PR #1170)
 - Added type validation for redirect uri, client ID, client secret, scopes, auth code, state, username, and password inputs (PR #1210)