Avoid leaking opened files

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: lfoppiano

grobid_client/format/TEI2LossyJSON.py

@@ -39,7 +39,8 @@ def convert_tei_file(self, tei_file: Union[Path, BinaryIO], stream: bool = False
         If stream=False returns the full document dict (same shape as original function).
         """
         # Load with BeautifulSoup but avoid building huge structures when streaming
-        content = open(tei_file, 'r').read()
+        with open(tei_file, 'r') as f:
+            content = f.read()
         soup = BeautifulSoup(content, 'xml')
 
         if soup.TEI is None: