fix: Remove accidentally doubled bracket in f-string (ietf-tools#5365)

Author: jennifer-richards

ietf/ietfauth/views.py

@@ -131,7 +131,7 @@ def create_account(request):
                 if to_email:
                     send_account_creation_exists_email(request, new_account_email, to_email)
                 else:
-                    raise ValidationError(f"Account for {{new_account_email}} exists, but cannot email it")
+                    raise ValidationError(f"Account for {new_account_email} exists, but cannot email it")
             else:
                 # For the IETF 113 Registration period (at least) we are lowering the
                 # barriers for account creation to the simple email round-trip check