Bug#871019: sshfs: Please update to 3.x

[Mo Zhou]

I guess sshfs 3.X is hopeless for Buster.
Because there is no any related transition on the tracker.

And fuse3 breaks gnome-core.

Anyone who cannot wait for the official package could try mine:
https://salsa.debian.org/lumin/sshfs-fuse  (3.5.1)