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 49f1cf8197800576b083614284c42531bb6df5ed)
(cherry picked from commit 35f2aacc3f1933f20fe603b35e0e6589132effe6)
(squashed)