matplotlib should not Build-Depend on ipython

[Jeremy Bícha]

matplotlib is the last package that has a dependency on ipython (currently provided by source: ipython-py2). Once ipython-py2 is removed, there are 3 packages stuck in the output report that will be able to migrate to focal.

This dependency was fixed in Debian, so I'm backporting the dependency update and filing this bug for the benefit of the Ubuntu release team since matplotlib is a seeded package.

https://people.canonical.com/~ubuntu-archive/proposed-migration/update_output.txt

[Launchpad Janitor (janitor)]

This bug was fixed in the package matplotlib - 3.1.2-1ubuntu4

---------------
matplotlib (3.1.2-1ubuntu4) focal; urgency=medium

  [ Sandro Tosi ]
  * debian/control
    - replace `ipython` with `python3-ipython`: mpl requires
      ipython_console_highlighting to build its doc, which is now in the latter
      package (LP: #1872596)

 -- Jeremy Bicha <email address hidden> Tue, 14 Apr 2020 00:04:39 -0400