Bump notebook from 6.4.1 to 6.4.12

Bumps [notebook](http://jupyter.org) from 6.4.1 to 6.4.12.

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

dev-requirements.txt

@@ -36,7 +36,7 @@ nbclient==0.5.3
 nbconvert==6.3.0
 nbformat==5.1.3
 nest-asyncio==1.5.1
-notebook==6.4.1
+notebook==6.4.12
 numpy==1.22.0
 -e git+https://github.com/banditml/offline-policy-evaluation.git@2e8035273e6d7533c801c4dee874f178bfda1541#egg=offline_evaluation
 packaging==20.9