Update fr.po: corrected a typo since "date" and "heure" are feminin, "és" -> "ées"

Hello :),

Thanks for your hard work :).

I had a regression on my laptop with Ubuntu,

some automatic process stopped working

(I download some URLs by emulating keyboard inputs in Firefox using Python :) ),

and I searched all panels in settings to see if something changed,

like an idiot ;) but I was bored and fed up :(.

I found this typo whilst looking at all settings.

Best regards,

Laurent Lyaudet