fix: don't free gametime, it is stack-allocated

src/game/gametime.h

@@ -1,6 +1,5 @@
 #pragma once
 
-#include <stdlib.h>
 #include <time.h>
 
 #include "../util/attributes.h"
@@ -25,10 +24,6 @@ atrb_const static inline gametime gametime_new(void) {
 	};
 }
 
-static inline void gametime_free(gametime* gt) {
-	free(gt);
-}
-
 // updates the internal variables
 static inline void gametime_update(gametime* gt) {
 	struct timespec ts;