add custom image model, fetch alt text

dnscms/associations/models.py

@@ -52,7 +52,7 @@ class AssociationPage(Page):
         max_length=64, choices=AssociationType, default=AssociationType.FORENING
     )
     logo = models.ForeignKey(
-        "wagtailimages.Image",
+        "images.CustomImage",
         null=True,
         blank=True,
         on_delete=models.SET_NULL,