Translated using Weblate (French) (#397)

Currently translated at 100.0% (29 of 29 strings)

Translation: Gaphor/gaphor.org Strings
Translate-URL: https://hosted.weblate.org/projects/gaphor/gaphor-org-strings/fr/

Co-authored-by: Vixepti <contact@vixepti.fr>

Author: weblate

_data/fr/strings.yml

@@ -50,5 +50,6 @@ footer:
   tech-docs: 'Lire la documentation'
   copyright: 'Copyright © 2020, The Gaphor Development Team.'
   theme: 'Thème'
+  mastodon: Mastodon
 languages:
   change: 'Changement'