fix nested "

src/pydiverse/transform/_internal/ops/op.py

@@ -76,6 +76,6 @@ def return_type(self, signature: Sequence[Dtype]) -> Dtype:
         if match is None:
             raise TypeError(
                 f"operator `{self.name}` cannot be called with arguments of type "
-                f"{", ".join(str(t) for t in signature)}"
+                f'{", ".join(str(t) for t in signature)}'
             )
         return match[1]