Map XAdES schemas correctly

Author: kislyuk

signxml/processor.py

@@ -18,7 +18,8 @@
 
 @lru_cache
 def get_schema(schema_file: str) -> etree.XMLSchema:
-    schema_fh = importlib.resources.open_text("signxml.schemas", schema_file)
+    pkg_name = "signxml.xades.schemas" if schema_file.startswith("XAdES") else "signxml.schemas"
+    schema_fh = importlib.resources.open_text(pkg_name, schema_file)
     return etree.XMLSchema(etree.parse(schema_fh))