Update neon litmus library

[nickvergessen]

We might want to consider updating to a recent version instead?
http://www.webdav.org/neon/

neon

The neon website has moved to https://notroj.github.io/neon/

Which has a 0.34.2 instead of 0.13

Originally posted by @nickvergessen in #634 (comment)

[nickvergessen]

@ChristophWurst is this something your team could look into?

[susnux]

@nickvergessen see also the long running server ticket: nextcloud/server#39627

The problem here is that Sabre/DAV is not complient with WebDAV RFC regarding Depth header handling.
I created a PR on sabre, but still waiting to be merged: sabre-io/dav#1495