fix(extras): Pydantic Rut type regex is not compliant with JSON Schema

The regular expression used to validate RUTs in `_RutPydanticAnnotation`
results in Pydantic generating an invalid JSON Schema because the
regex uses named groups, which are not supported by the JavaScript
regular expression syntax used by JSON Schema (and OpenAPI).

Author: jtrobles-cdd

src/cl_sii/extras/pydantic_types.py

@@ -4,8 +4,9 @@
 
 from __future__ import annotations
 
+import re
 import sys
-from typing import Any
+from typing import Any, ClassVar, Pattern
 
 
 if sys.version_info[:2] >= (3, 9):
@@ -74,6 +75,21 @@ class _RutPydanticAnnotation:
     b'"78773510-K"'
     """
 
+    RUT_CANONICAL_STRICT_REGEX: ClassVar[Pattern] = re.compile(
+        re.sub(
+            pattern=r'\?P<\w+>',
+            repl='',
+            string=cl_sii.rut.constants.RUT_CANONICAL_STRICT_REGEX.pattern,
+        )
+    )
+    """
+    RUT (strict) regex for canonical format, without named groups.
+
+    .. warning::
+        JSON Schema and OpenAPI use the regular expression syntax from
+        JavaScript (ECMA 262), which does not support Python’s named groups.
+    """
+
     @classmethod
     def __get_pydantic_core_schema__(
         cls, source_type: Any, handler: pydantic.GetCoreSchemaHandler
@@ -83,9 +99,7 @@ def validate_from_str(value: str) -> cl_sii.rut.Rut:
 
         from_str_schema = pydantic_core.core_schema.chain_schema(
             [
-                pydantic_core.core_schema.str_schema(
-                    pattern=cl_sii.rut.constants.RUT_CANONICAL_STRICT_REGEX.pattern
-                ),
+                pydantic_core.core_schema.str_schema(pattern=cls.RUT_CANONICAL_STRICT_REGEX),
                 pydantic_core.core_schema.no_info_plain_validator_function(validate_from_str),
             ]
         )