Update specfile/sections.py

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: nforro

specfile/sections.py

@@ -174,7 +174,7 @@ def __contains__(self, id: object) -> bool:
         except AttributeError:
             return False
         if isinstance(id, str):
-            id_lower = cast(str, id).lower()
+            id_lower = id.lower()
             return any(
                 s.normalized_id == id_lower or s.normalized_name == id_lower
                 for s in data