Update latest version to 7.0.0 (#20469)

build/Dockerfile

@@ -4,7 +4,7 @@ FROM alpine:3.14.6@sha256:06b5d462c92fc39303e6363c65e074559f8d6b1363250027ed5053
 ENV PATH="/mattermost/bin:${PATH}"
 ARG PUID=2000
 ARG PGID=2000
-ARG MM_PACKAGE="https://releases.mattermost.com/6.7.1/mattermost-6.7.1-linux-amd64.tar.gz?src=docker"
+ARG MM_PACKAGE="https://releases.mattermost.com/7.0.0/mattermost-7.0.0-linux-amd64.tar.gz?src=docker"
 
 
 # Install some needed packages