bump base for [build] djvulibre: add Kobo always UTF-8 filenames patch (#3845)
bump base for [build] djvulibre: add Kobo always UTF-8 filenames patch (#3845)

https://github.com/koreader/koreader-base/pull/639

Fixes #542.
Frenzie/koreader,poire-z/koreader,Markismus/koreader,NiLuJe/koreader,koreader/koreader,mihailim/koreader,NiLuJe/koreader,poire-z/koreader,houqp/koreader,lgeek/koreader,Frenzie/koreader,pazos/koreader,koreader/koreader,Hzj-jie/koreader,mwoz123/koreader