Fix syntax

aleksis/core/models.py

@@ -1437,7 +1437,7 @@ class PersonInvitation(AbstractBaseInvitation, PureDjangoModel):
     def send_invitation(self, request, **kwargs):
         """Send the invitation email to the person."""
         # TODO: Use correct URL to new signup wizard
-        invite_url = f"{reverse("account_signup")}?invitation_code={self.key}"
+        invite_url = f"{reverse('account_signup')}?invitation_code={self.key}"
         invite_url = request.build_absolute_uri(invite_url).replace("/django", "")
         context = kwargs
         context.update(