• Add mixin annotation for Token model in AccessToken by @fjkorf in #1886
• Add dedicated token lifetime for client credentials grant by @sajanp in #1880
• Add missing OAuthenticatable interface step to upgrade guide by @FeBe95 in #1887
• Improve code syntax highlighting in upgrade guide by @FeBe95 in #1890
• Allow custom middleware to be registered by @timacdonald in #1892
• Update UPGRADE.md by @siarheipashkevich in #1891