gnucash maint: Fix broken month in aqbanking<6 import

[Christian Stimming]

Updated	 via  https://github.com/Gnucash/gnucash/commit/b36a0125 (commit)
	from  https://github.com/Gnucash/gnucash/commit/d6ceec68 (commit)



commit b36a01251272011b05cc35cde6d9d422dcdfaa2f
Author: Christian Stimming <christian at cstimming.de>
Date:   Wed Jul 29 22:01:52 2020 +0200

    Fix broken month in aqbanking<6 import
    
    The used GWEN_Time_GetBrokenDownDate returns month in interval [0..11].



Summary of changes:
 gnucash/import-export/aqb/gnc-ab-utils.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)