Updated admin.py

Created admins for the 3 models, and registered them accordingly.

agusyquia_music/homepage/admin.py

 from django.contrib import admin
+from.models import Artist, Album, Song
 
 # Register your models here.
+class ArtistAdmin(admin.ModelAdmin):
+    model = Artist
+
+class AlbumAdmin(admin.ModelAdmin):
+    model = Album
+
+class SongAdmin(admin.ModelAdmin):
+    model = Song
+
+admin.site.register(Artist, ArtistAdmin)
+admin.site.register(Album, AlbumAdmin)
+admin.site.register(Song, SongAdmin)
\ No newline at end of file