Fix error in determin systemd support for debian 13 and newer.

check_cert_coolwsd.sh

@@ -145,12 +145,12 @@ fi
 
 # - Systemd supported ?
 # -
-systemd_supported=false
+SYSTEMD_EXISTS=false
 systemd=$(which systemd)
 systemctl=$(which systemctl)
 
-if [[ -n "$systemd" ]] && [[ -n "$systemctl" ]] ; then
-   systemd_supported=true
+if [[ -n "$systemd" ]] || [[ -n "$systemctl" ]] ; then
+   SYSTEMD_EXISTS=true
 fi
 
 
@@ -382,7 +382,7 @@ if ! diff "$(realpath "$cert_installed")" "$(realpath "$cert_newest")" > /dev/nu
       # -
 		echo ""
 		echononl "   Restart Service '$SERVICE_NAME'.."
-      if $systemd_supported ; then
+      if $SYSTEMD_EXISTS ; then
 
          systemctl restart "$SERVICE_NAME" > $log_file 2>&1