Log Message:
py-notebook: updated to 5.7.8

5.7.8
- Fix regression in restarting kernels in 5.7.5.
  The restart handler would return before restart was completed.
- Further improve compatibility with tornado 6 with improved
  checks for when websockets are closed.
- Fix regression in 5.7.6 on Windows where .js files could have the wrong mime-type.
- Fix Open Redirect vulnerability (CVE-2019-10255)
  where certain malicious URLs could redirect from the Jupyter login page
  to a malicious site after a successful login.
  5.7.7 contained only a partial fix for this issue.