Bump mistune from 0.8.4 to 2.0.3

Bumps [mistune](https://github.com/lepture/mistune) from 0.8.4 to 2.0.3.
- [Release notes](https://github.com/lepture/mistune/releases)
- [Changelog](https://github.com/lepture/mistune/blob/master/docs/changes.rst)
- [Commits](lepture/mistune@v0.8.4...v2.0.3)

---
updated-dependencies:
- dependency-name: mistune
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -39,7 +39,7 @@ jupyter-core==4.6.3
 Keras-Preprocessing==1.1.2
 Markdown==3.2.2
 MarkupSafe==1.1.1
-mistune==0.8.4
+mistune==2.0.3
 msgpack==0.6.2
 multidict==4.7.6
 nbconvert==6.3.0