fix: [mattermost] postgres password is saved in config, so we need also to change it.

mattermost/hooks/postgres_database-relation-joined

@@ -18,6 +18,9 @@ services:
       MM_USERNAME: $USER
 "
 
+sed -ri  's/(^\s+"DataSource": "postgres:[^:]+:)([^@]+)@/\1'"$PASSWORD"'@/' \
+    "$SERVICE_CONFIGSTORE/mattermost/config/config.json" || exit 1
+
 [ "$control" == "$(relation-get control 2>/dev/null)" ] && exit 0