math/py-igraph: 0.11.9 update, fixes libxml2 use

with its slightly changed xmlerror.h API.
drop unneeded _DEPENDS

Approved by:	lwhsu@ (maintainer timeout, 12+ months)
PR:		279961
Reported by: 	diizzy@
MFH:		2025Q3

(cherry picked from commit 49f1cf81)
(cherry picked from commit 35f2aacc)
(squashed)