Setting prosody group

src/freedombone-app-xmpp

 
 function upgrade_xmpp {
     if [ -d /etc/letsencrypt ]; then
-        usermod -a -G ssl-cert prosody
+        prosody_groups=$(groups prosody)
+        if [[ "$prosody_groups" != *'ssl-cert'* ]]; then
+            usermod -a -G ssl-cert prosody
+        fi
     fi
     function_check update_prosody_modules
     update_prosody_modules