Bump notebook from 6.4.10 to 6.4.12 in /requirements/py39-reqs (#436)

Bumps [notebook](http://jupyter.org) from 6.4.10 to 6.4.12.

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

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements/py39-reqs/docs.txt

@@ -217,7 +217,7 @@ nest-asyncio==1.5.4
     #   jupyter-client
     #   nbclient
     #   notebook
-notebook==6.4.10
+notebook==6.4.12
     # via snafu (setup.cfg)
 numpy==1.22.1
     # via