[templates] Clean up how str and subtitles work

vrobbler/apps/scrobbles/mixins.py

@@ -65,6 +65,9 @@ class ScrobblableMixin(TimeStampedModel):
     class Meta:
         abstract = True
 
+    def __str__(self) -> str:
+        return f"{self.title} - {self.subtitle}"
+
     @property
     def run_time_seconds(self) -> int:
         run_time = 900