made the switch to using bracket-lib directly, instead of rltk wrapper

this should solve the build issues; it makes using the non-crashing github build a lot easier, because it lets the explicit rltk dependency be removed.

src/lib.rs

@@ -1,7 +1,7 @@
 // src/lib.rs
 // 31-Aug-2023
 
-use rltk::prelude::*;
+use bracket_lib::prelude::*;
 use specs::prelude::*;
 extern crate serde;