gnucash maint: Update txt-to-pot.sh's header to gettext-tools 0.19.8.1

[Frank H.Ellenberger]

Updated	 via  https://github.com/Gnucash/gnucash/commit/0f815d9d (commit)
	from  https://github.com/Gnucash/gnucash/commit/0543a290 (commit)



commit 0f815d9d1d01c3208a4405f18194416cb236e6c0
Author: Frank H. Ellenberger <frank.h.ellenberger at gmail.com>
Date:   Sat Jun 29 11:29:58 2019 +0200

    Update txt-to-pot.sh's header to gettext-tools 0.19.8.1
    
    In the last 2 decades a few parameters were added



Summary of changes:
 po/glossary/txt-to-pot.sh | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)