Load json schema with parse_float as decimal

Float value in the json schema are used in arithmetic division. They must be loaded as decimal or comparison will fail.
see RedHatProductSecurity#87

cvelib/cve_api.py

@@ -51,7 +51,7 @@ def validate(cls, cve_json: dict, schema_path: Optional[str] = None) -> None:
             schema_path = cls.Schemas.CNA_PUBLISHED
 
         with open(schema_path) as schema_file:
-            schema = json.load(schema_file)
+            schema = json.load(schema_file, parse_float=decimal.Decimal)
 
         validator = Draft7Validator(schema)
         errors = sorted(validator.iter_errors(cve_json), key=lambda e: e.message)