bump version

Upgrade discussion
https://github.com/orgs/docker-mailserver/discussions/4046

Signed-off-by: Aldo Maria Vizcaino <aldo.vizcaino87@gmail.com>

Author: AlMaVizca

charts/docker-mailserver/Chart.yaml

@@ -1,8 +1,8 @@
 apiVersion: v2
-appVersion: "13.3.1"
+appVersion: "14.0.0"
 description: A fullstack but simple mailserver (smtp, imap, antispam, antivirus, ssl...) using Docker.
 name: docker-mailserver
-version: 3.0.13
+version: 4.0.0
 sources:
 - https://github.com/docker-mailserver/docker-mailserver-helm
 maintainers: