luci-app-opkg: relax dependency parsing

Align depdendency parse logic with opkg to properly process certain
malformed dependency specifications. In particular do not require a
depdendency specification to end after the closing paren of a version
constraint and perform non-greedy matching in order to extract the
first version constraint only.

Fixes: #5997
Ref: https://forum.openwrt.org/t/x/138328
Signed-off-by: Jo-Philipp Wich <jo@mein.io>