Make CveRecordValidationError picklable

This prevents PicklingError errors when the exception is stored e.g. by
Celery when creating TaskResult records:

```
{"exc_type": "MaybeEncodingError", "exc_message":
["'PicklingError(\"Can\\'t pickle <class
\\'cvelib.cve_api.CveRecordValidationError\\'>: it\\'s not the same
object as cvelib.cve_api.CveRecordValidationError\")'", "\"(1,
<ExceptionInfo: CveRecordValidationError('Schema validation against
/usr/local/lib/python3.9/site-packages/cvelib/schemas/published_cna_container_5.0.0.json
failed')>, None)\""], "exc_module": "billiard.pool"}
```

cvelib/cve_api.py

@@ -21,9 +21,13 @@ def __str__(self) -> str:
 
 
 class CveRecordValidationError(Exception):
-    def __init__(self, message, errors):
-        super().__init__(message)
+    def __init__(self, *args, **kwargs):
+        errors = kwargs.pop("errors", None)
         self.errors = errors
+        super().__init__(*args, **kwargs)
+
+    def __reduce__(self):
+        return CveRecordValidationError, (self.args,)
 
 
 class CveRecord:
@@ -54,7 +58,7 @@ def validate(cls, cve_json: dict, schema_path: Optional[str] = None) -> None:
         if errors:
             errors_str = "\n".join(e.message for e in errors)
             raise CveRecordValidationError(
-                f"Schema validation against {schema_path} failed:\n{errors_str}", errors
+                f"Schema validation against {schema_path} failed:\n{errors_str}", errors=errors
             )
 
 

tests/test_cve_api.py

@@ -1,4 +1,5 @@
 import json
+import pickle
 from pathlib import Path
 
 import pytest
@@ -38,3 +39,17 @@ def test_invalid_record_schema_validation():
     exc_errors = exc_info._excinfo[1].errors
     assert "'providerMetadata' is a required property" in exc_errors[0].message
     assert "'rejectedReasons' is a required property" in exc_errors[1].message
+
+
+def test_cve_record_validation_error_is_picklable():
+    try:
+        CveRecord.validate({})
+    except CveRecordValidationError as exc:
+        assert "'affected' is a required property" in str(exc)
+        assert "'affected' is a required property" == exc.errors[0].message
+        pickled = pickle.dumps(exc)
+        unpickled_exc = pickle.loads(pickled)
+        assert "'affected' is a required property" in str(unpickled_exc)
+        # Errors do not survive pickling because they include jsonschema-specific objects that
+        # are not picklable.
+        assert unpickled_exc.errors is None