feat: improve notes imports by using de-gfm -4. Related to #3851. (#3930)

ietf/utils/hedgedoc.py

@@ -95,8 +95,8 @@ def de_gfm(source: str):
     Calls de-gfm from the kramdown-rfc2629 gem.
     """
     result = subprocess.run(
-        [settings.DE_GFM_BINARY,],
-        stdout=subprocess.PIPE,  # post-Python 3.7, this can be replaced with capture_output=True
+        [settings.DE_GFM_BINARY, "-4"],
+        capture_output=True,
         input=source,
         encoding='utf8',
         check=True,
@@ -123,4 +123,4 @@ class NoteNotFound(NoteError):
 
 
 class InvalidNote(NoteError):
-    default_message = 'Note data invalid'
+    default_message = 'Note data invalid'