mk/orgcard2txt.pl: Get version from org-version.tex

See https://list.orgmode.org/orgmode/20221018181338.74812f94@debian/

Reported-by: Norwid Behrnd <nbehrnd@yahoo.com>
Acked-by: Ihor Radchenko <yantar92@posteo.net>

mk/orgcard2txt.pl

@@ -45,7 +45,7 @@ sub rep_esc{
 my $page=0;
 my $orgversionnumber;
 
-open(IN,$ARGV[0]);
+open(IN,"org-version.tex");
 while(<IN>){
   last if(/\f/);
   $orgversionnumber = $1 if /\\def\\orgversionnumber{([^}]+)}/;