Refactor attribute filtering in PlexObject class (#1341)

* Refactor attribute filtering in PlexObject class

- minor performance imporvement

* Update plexapi/base.py

Co-authored-by: JonnyWong16 <[email protected]>

---------

Co-authored-by: JonnyWong16 <[email protected]>

Author: Dr-Blank

Diff for: plexapi/base.py

@@ -440,7 +440,7 @@ def _getAttrValue(self, elem, attrstr, results=None):
         attrstr = parts[1] if len(parts) == 2 else None
         if attrstr:
             results = [] if results is None else results
-            for child in [c for c in elem if c.tag.lower() == attr.lower()]:
+            for child in (c for c in elem if c.tag.lower() == attr.lower()):
                 results += self._getAttrValue(child, attrstr, results)
             return [r for r in results if r is not None]
         # check were looking for the tag