Syntax error in bones.sv.tr

[Wuzzy2]

With a script I discovered 2 syntax errors in bones.sv.tr. There is a missing placeholder in the translations.

Thankfully, there is an upstream fix in Minetest Game, so you can just copy it: https://github.com/minetest/minetest_game/pull/3021/files

(FYI: I have found this with this script: https://codeberg.org/Wuzzy/minetest_check_translations)