Updates weechat to 0.4.1 and fixes python support

This patch upgrades weechat to 0.4.1 as well as fixing the cmake issues that lead to python errors as reported in #19300 and #19168.

Basically cmake is searching a cmake defined list of paths as well as the ones that weechat's cmake scripts define. This is leading to both system and brewed versions of python being picked up together.