Fix encoding issue is PhyloExport label
Fixes purescript-gargantext#632 (closed)
This MR changes as little as possible; I would like to issue a follow-up to this MR with general improvements to PhyloExport
alongside what I recommended previously here;
However, I don't want to change too much, too soon, to not break the current Phylo exporting, as we currently don't have any valid regression test to catch errors.