fix: two gametimes were present

src/game/gametime.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <stdlib.h>
 #include <time.h>
 
 typedef struct {
@@ -22,6 +23,10 @@ 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;