Don't fail tests on harmless changes to dependencies

Don't fail tests on harmless changes to dependencies

Ignore deprecation warnings added in
Python 3.8, matplotlib 3.2, jedi 0.16/0.17
(one jedi deprecation appears to come from IPython because it uses stacklevel=2)

Don't assert that matplotlib rejects shorthand hex colors,
as from 3.2 it accepts them:
https://matplotlib.org/users/prev_whats_new/whats_new_3.2.0.html#digit-and-4-digit-hex-colors

Ignore change to date axis default range/ticks

Author: Rebecca N. Palmer <rebecca_palmer@zoho.com>
Forwarded: no

Gbp-Pq: Name ignore_matplotlib_warning.patch