Fix test incompatibility with newer PyTensor check

Author: ricardoV94

tests/distributions/test_custom.py

@@ -287,7 +287,7 @@ def test_multivariate_insufficient_signature(self):
         with pytest.raises(
             NotImplementedError, match="signature is not sufficient to infer the support shape"
         ):
-            CustomDist.dist(signature="(n)->(m)")
+            CustomDist.dist([0], signature="(n)->(m)")
 
 
 class TestCustomSymbolicDist: