Update lubimycztac metadata provider (fixes #3090)

cps/metadata_provider/lubimyczytac.py

@@ -285,11 +285,13 @@ class LubimyCzytacParser:
 
     def _parse_tags(self) -> List[str]:
         tags = self._parse_xpath_node(xpath=LubimyCzytac.TAGS, take_first=False)
+        if tags:
             return [
                 strip_accents(w.replace(", itd.", " itd."))
                 for w in tags
                 if isinstance(w, str)
             ]
+        return None
 
     def _parse_from_summary(self, attribute_name: str) -> Optional[str]:
         value = None