schema: adds ability to get PRefine within extension parent_node

This patch adds ability to get also PRefine as a valid output using
extension parent_node function

Signed-off-by: Stefan Gula <steweg@gmail.com>

Author: steweg

libyang/schema.py

@@ -423,10 +423,13 @@ def name(self) -> str:
     def module(self) -> Module:
         return self._module_from_parsed()
 
-    def parent_node(self) -> Optional[Union["PNode", "PIdentity"]]:
+    def parent_node(self) -> Optional[Union["PNode", "PIdentity", "PRefine"]]:
         if self.cdata.parent_stmt == lib.LY_STMT_IDENTITY:
             cdata = ffi.cast("struct lysp_ident *", self.cdata.parent)
             return PIdentity(self.context, cdata, self.module_parent)
+        if self.cdata.parent_stmt == lib.LY_STMT_REFINE:
+            cdata = ffi.cast("struct lysp_refine *", self.cdata.parent)
+            return PRefine(self.context, cdata, self.module_parent)
         if bool(self.cdata.parent_stmt & lib.LY_STMT_NODE_MASK):
             try:
                 return PNode.new(self.context, self.cdata.parent, self.module_parent)