MFH: r492577 r494977 r495995
Update to 5.7.4
Changes: https://github.com/jupyter/notebook/releases
https://github.com/jupyter/notebook/blob/master/docs/source/changelog.rst
Update to 5.7.5
Changes: https://github.com/jupyter/notebook/releases
https://github.com/jupyter/notebook/blob/master/docs/source/changelog.rst
Update to 5.7.6
Changes: https://github.com/jupyter/notebook/releases
https://github.com/jupyter/notebook/blob/master/docs/source/changelog.rst
Security: 72a6e3be-483a-11e9-92d7-f1590402501e
Approved by: ports-secteam (joneum)