Replace Minetest mentions with Luanti (#3169)

mods/player_api/README.txt

@@ -9,7 +9,7 @@ This mod is only for content related to the Player API and the player object.
 Authors of source code
 ----------------------
 Originally by celeron55, Perttu Ahola <celeron55@gmail.com> (LGPLv2.1+)
-Various Minetest developers and contributors (LGPLv2.1+)
+Various Minetest Game developers and contributors (LGPLv2.1+)
 
 Authors of media (textures, models and sounds)
 ----------------------------------------------

mods/player_api/license.txt

@@ -3,7 +3,7 @@ License of source code
 
 GNU Lesser General Public License, version 2.1
 Copyright (C) 2011 celeron55, Perttu Ahola <celeron55@gmail.com>
-Copyright (C) 2011 Various Minetest developers and contributors
+Copyright (C) 2011 Various Minetest Game developers and contributors
 
 This program is free software; you can redistribute it and/or modify it under the terms
 of the GNU Lesser General Public License as published by the Free Software Foundation;