This update contains a SECURITY fix for an issue with potentially serious consequences but very limited scope. If an administrator of a wiki you talked to using python-wikitcms were malicious, they could cause arbitrary code execution as the user running wikitcms. No-one besides a wiki administrator could do this, as it requires crafting the wiki’s response to an edit request to include a malicious payload.
It also drops some now useless or unneeded code (due to changes in mediawiki and mwclient).