Update mumble certs during upgrades

src/freedombone-app-mumble

     if [ -d /etc/letsencrypt ]; then
         usermod -a -G ssl-cert mumble-server
     fi
+
+    if [ ! -f /etc/letsencrypt/live/${DEFAULT_DOMAIN_NAME}/fullchain.pem ]; then
+        if ! grep -q "mumble.pem" /etc/mumble-server.ini; then
+            sed -i 's|sslCert=.*|sslCert=/var/lib/mumble-server/mumble.pem|g' /etc/mumble-server.ini
+            sed -i 's|sslKey=.*|sslKey=/var/lib/mumble-server/mumble.key|g' /etc/mumble-server.ini
+            systemctl restart mumble
+        fi
+    else
+        if ! grep -q "${DEFAULT_DOMAIN_NAME}/fullchain.pem" /etc/mumble-server.ini; then
+            usermod -a -G ssl-cert mumble-server
+            sed -i "s|sslCert=.*|sslCert=/etc/letsencrypt/live/${DEFAULT_DOMAIN_NAME}/fullchain.pem|g" /etc/mumble-server.ini
+            sed -i "s|sslKey=.*|sslKey=/etc/letsencrypt/live/${DEFAULT_DOMAIN_NAME}/privkey.pem|g" /etc/mumble-server.ini
+            systemctl restart mumble
+        fi
+    fi
 }
 
 function backup_local_mumble {