Update zmupdate.pl.in for 1.26.3 release

Will github let us delete the existing 1.26.3 release and re-create it with this commit?  We need to make a change similar to this commit just prior to any new release. Otherwise we re-create issue#114.

@kylejohnson
Looks like you beat me to this change.  I'll delete this pull request once it is confirmed that it is not needed.