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

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