Update to upstream version '2.4.2'
with Debian dir 196d5f227c50e9b78022da184ababc6ee414f976

There is a regression that breaks attr.evolve() when updating attributes
that contain an attr class; which we use (eg. for Person or TimestampWithTimezone).

v21.2.0 is expected to fix the issue, but won't be released immediately:
https://github.com/python-attrs/attrs/issues/804#issuecomment-833471190

Update to upstream version '2.4.1'
with Debian dir e9d4ffb7ab9423c2de37dacd4c8c388935711fd5

Enable to check package documentation can be built without producing
sphinx warnings.

The sphinx environment is designed to be used in continuous integration
in order to prevent breaking documentation build when committing changes.

The sphinx-dev environment is designed to be used inside a full swh
development environment.

Related to T3258

and add a test to keep them correct.

Update to upstream version '2.4.0'
with Debian dir e87ccb4fa17d1fa370c7d13de36ba753221112db

According to the SWHID specification, it is not forbidden for a qualifier
value to contain a '=' character (for instance in origin URL).

So update parsing code to handle that special case.

Some ValidationError exceptions could not be serialized to string due
to these format errors.

Related to T3234

Otherwise, they will get an error asking them to install Click
(or Dulwich if Click installed and they use -t snapshot)

And show nice human-readable errors instead

Was added in be8f1a55

Some releases don't have authors and date fields, this case should be
checked in the tests.

Update to upstream version '2.3.0'
with Debian dir 226b10fe808b4f706ee02cac31636de44440044f

This truncation is already enshrined at the identifier level. Truncate
the object itself as well, to reduce the possibility multiple different
metadata objects with the same identifier.

Update to upstream version '2.2.0'
with Debian dir 15ac67e7278dc66e127e288ac4589a3d1bc460fb

All other hashable objects but ExtId have one.

It will be used by swh-deposit.

Update to upstream version '2.1.0'
with Debian dir 6b5419fe87be223d70c9630dfdc5de683ccac7f3

this object aims at being able to keep in the SWH Archive an
  SWHID <-> External object ID
map, e.g. to be able to keep track of Mercurial ids so the Mercurial
loader can be made more efficient.

Related to T2849.

was modifying the dict given as argument.

Update to upstream version '2.0.0'
with Debian dir 40768420e535abdbc97e85502bba4b26414a1ea8