Capitalize author in game.conf to match ContentDB

The author is used to track packages for updating, so it should match.
2019-05-26 15:16:53 -04:00 · 2019-05-26 15:16:53 -04:00 · 80c10cee15
--- a/game.conf
+++ b/game.conf
@ -1,3 +1,3 @@
 name = Minetest Game
-author = minetest
+author = Minetest
 description = Bundled by default with Minetest, and aims to be lightweight, moddable, and fairly playable without mods.