backend/segmenter: Sanitize EcoTaxa export filename for problematic special characters

[gromain]

At https://github.com/PlanktonPlanet/PlanktoScope/blob/73318d28a48d8521e0f00426ad29d45dd0886664/scripts/planktoscope/segmenter/__init__.py#L859

[ethanjli]

Spaces are already replaced with underscores; I am expanding this issue to also cover the need to replace other special characters which EcoTaxa might not like. I think the first step here will be to figure out which special characters EcoTaxa cannot handle properly.

[ethanjli]

This issue is related to #422, and might even be a generalization of it.