downgrade validator to maintain behavior for correct draft for v1.0.0 HiFa

Author: kratsg

src/pyhf/schema/validator.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import numbers
 
 import jsonschema
@@ -7,7 +9,6 @@
 from pyhf import tensor
 from pyhf.schema import variables
 from pyhf.schema.loader import load_schema
-from typing import Union
 from pyhf.typing import Workspace, Model, Measurement, PatchSet
 from typing import Any
 
@@ -41,10 +42,10 @@ def _is_number_or_tensor_subtype(
 
 
 def validate(
-    spec: Union[Workspace, Model, Measurement, PatchSet],
+    spec: Workspace | Model | Measurement | PatchSet,
     schema_name: str,
     *,
-    version: Union[str, None] = None,
+    version: str | None = None,
     allow_tensors: bool = True,
 ) -> None:
     """
@@ -95,6 +96,10 @@ def validate(
 
     Validator = jsonschema.Draft202012Validator
 
+    # downgrade Validator for v1.0.0
+    if version == '1.0.0':
+        Validator = jsonschema.Draft6Validator  # type: ignore[assignment]
+
     if allow_tensors:
         type_checker = Validator.TYPE_CHECKER.redefine(
             "array", _is_array_or_tensor