setup.py: Updated Markdown dependency to v2.4
setup.py: Updated Markdown dependency to v2.4

shadowoneau/skylines,Harry-R/skylines,snip/skylines,skylines-project/skylines,RBE-Avionik/skylines,Turbo87/skylines,Turbo87/skylines,Turbo87/skylines,skylines-project/skylines,Harry-R/skylines,snip/skylines,TobiasLohner/SkyLines,skylines-project/skylines,skylines-project/skylines,shadowoneau/skylines,Turbo87/skylines,shadowoneau/skylines,TobiasLohner/SkyLines,kerel-fs/skylines,shadowoneau/skylines,snip/skylines,TobiasLohner/SkyLines,Harry-R/skylines,kerel-fs/skylines,RBE-Avionik/skylines,RBE-Avionik/skylines,Harry-R/skylines,kerel-fs/skylines,RBE-Avionik/skylines