gnucash maint: L10N:de: fix a plural error

[Frank H.Ellenberger]

Updated	 via  https://github.com/Gnucash/gnucash/commit/29003da7 (commit)
	from  https://github.com/Gnucash/gnucash/commit/3f712037 (commit)



commit 29003da7a41f2c8af26e170c5935905fa02887c8
Author: Frank H. Ellenberger <frank.h.ellenberger at gmail.com>
Date:   Sun Mar 21 09:29:31 2021 +0100

    L10N:de: fix a plural error
    
    Additional improve meaning, but no backport because of string freeze.



Summary of changes:
 po/de.po | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)