set PartialFunction's parent to adhoc module instead of Unknown

it's a part of the campaign to get rid of non-module roots

astroid/objects.py

@@ -282,7 +282,7 @@ def __init__(self, call, name=None, lineno=None, col_offset=None, parent=None):
             name,
             lineno=lineno,
             col_offset=col_offset,
-            parent=node_classes.Unknown(),
+            parent=AstroidManager().adhoc_module,
             end_col_offset=0,
             end_lineno=0,
         )