Update latest version to 6.6.0 (#19990)

Automatic Merge

build/Dockerfile

@@ -4,7 +4,7 @@ FROM alpine:3.14@sha256:635f0aa53d99017b38d1a0aa5b2082f7812b03e3cdb299103fe77b5c
 ENV PATH="/mattermost/bin:${PATH}"
 ARG PUID=2000
 ARG PGID=2000
-ARG MM_PACKAGE="https://releases.mattermost.com/6.4.1/mattermost-6.4.1-linux-amd64.tar.gz?src=docker"
+ARG MM_PACKAGE="https://releases.mattermost.com/6.6.0/mattermost-6.6.0-linux-amd64.tar.gz?src=docker"
 
 
 # Install some needed packages