[admin] Use raw ids where possible and simplify scrobble inlines

vrobbler/apps/podcasts/admin.py

@@ -18,6 +18,7 @@ class PodcastAdmin(admin.ModelAdmin):
         "producer",
         "active",
     )
+    raw_id_fields = ("producer",)
     ordering = ("name",)
 
 
@@ -28,6 +29,7 @@ class PodcastEpisodeAdmin(admin.ModelAdmin):
         "title",
         "podcast",
     )
+    raw_id_fields = ("podcast",)
     list_filter = ("podcast",)
     ordering = ("-created",)
     inlines = [