[arrow_signs] Change l'url du submodule

Et supprime sa branche

.gitmodules

@@ -15,8 +15,7 @@
 	url = https://sys4.fr/gitea/mff/areas.git
 [submodule "arrow_signs"]
 	path = arrow_signs
-	url = https://sys4.fr/gitea/nalc/arrow_signs.git
-	branch = mff
+	url = https://sys4.fr/gitea/mff/arrow_signs.git
 [submodule "automappercolors"]
 	path = automappercolors
 	url = https://sys4.fr/gitea/nalc/automappercolors.git