Bump nbconvert (#1145)

Author: dependabot[bot]

examples/pytorch/nlp/huggingface_models/common/examples/research_projects/lxmert/requirements.txt

@@ -43,7 +43,7 @@ matplotlib==3.3.1
 mistune==2.0.3
 msgpack==0.6.2
 nbclient==0.5.0
-nbconvert==6.0.1
+nbconvert==6.3.0
 nbformat==5.0.7
 nest-asyncio==1.4.0
 notebook==6.4.12