Add str function for highscores data.

data/highscores_data.py

@@ -28,6 +28,19 @@ class HighscoresData:
 
         self.open_highscores_data()
 
+    def __str__(self) -> str:
+        """
+        Returns Highscores class as a string for printing.
+
+        Returns:
+            str: Highscores class as a string
+        """
+        data: dict = {}
+        for guild_id, guild_obj in self._guild_map:
+            data[guild_id] = guild_obj.to_dict()
+
+        return "Highscores Data\n" + json.dumps(data, indent=4)
+
     def add_guild(self, guild_id: int) -> None:
         """
         Creates a new Guild and adds to Guild map.