use strict;
use DateTime;
use POSIX; 

my $SAMSTAG = 6;
my $SONNTAG = 7;

my $add_Geschaeftstage = 7;
my $dt = DateTime->now( time_zone => 'Europe/Paris' );

while ($add_Geschaeftstage) {
    $dt->add( days => 1 );
    $add_Geschaeftstage-- unless ( $dt->wday() == $SAMSTAG || $dt->wday() == $SONNTAG );
}
print $dt->strftime( "%d.%m.%Y" );