Update to upstream version '4.2.0'
with Debian dir 7f3220a0c36f412bcffe11641f3af52abc637717

This is needed when recomputing the manifest of git objects with weird offsets.

Update to upstream version '4.1.0'
with Debian dir a0f59d4b85b6e222399e244f593cd4dc5d89a2f6

blake2s and blake2b have been provided by the stdlib hashlib since
Python 3.6, and we declare 3.7 as minimum Python version supported.

Update to upstream version '4.0.0'
with Debian dir 0143bffc8b14df982ce96dfc4ee06b615eeff598

1. Most objects do not need it so it's a waste of space
2. This means we just extend the existing format (some objects will
   have that key in their dict) instead of changing it (retroactively
   adding it to all objects)

This will be used to store the original manifest of 'weird' git objects,
when we cannot reasonably represent them otherwise.

We don't store those

Revision and release do not generally allow 'arbitrary' metadata;
and it was missing ExtIDs and REMD

This also drops spurious copyright headers to those files if present.

Related to T3812

Using .now() produces data that differs between xdist processes,
as files are imported after forking, and xdist requires consistent
data across processes.

Update to upstream version '3.2.0'
with Debian dir 567243905bd218727970a1bcb2b8a702375619d1

It calls attr.validate() (which calls the validators), and recomputes
the hash of HashableObject instances.

A future commit will also make it check the raw_manifest attribute
when relevant

It's just simpler this way

For the sake of completeness (a future commit may depend on it).

For now it is filled from 'offset' and 'negative_utc', but it will replace them
in a future commit.

This is to simplify and add support for more 'weird' offsets we do not currently
support.

This reverts commit c525484e.

It enables to easily check if a path exists from a root directory.

Since rDMOD8d96dfedee34203a4118e48a6208ee507511590b, directory entry
names are validated in DirectoryEntry model and thus must not contain
any slash characters.

So update directory_entries_d hypothesis strategy to ensure such names
are generated to avoid flaky tests.

Update to upstream version '3.1.0'
with Debian dir 0d4cc11bcbd2ead6cb1d1f7d76b4b2bd219a2623

Enable to compute md5 sum through the hashutil.MultiHash class.

Nevertheless, md5 is not put in DEFAULT_ALGORITHMS set and must
be explicitely requested by client code.

Related to T2400

I don't know any instance of these, but there is no harm in checking them.

1. hashes are now repr()ed as `hash_to_bytes("1234...")` instead of b"\x12\x34..."`
2. SWHID objects are now repr()ed as `CoreSWHID.from_string('swh:1:...:1234...')`
   instead of `CoreSWHID(scheme='swh', version='1', object_type=..., object_id=b'\x12\x34')`
3. enums are now repr()ed as `MyEnum.NAME` instead of "<MyEnum.NAME: 'value'>`

Thanks to these three changes, using repr() on a model object now prints
a string that can be pasted directly in a `.py` file to write a new
test case.

The previous replaced attrs-strict's type validator with our own,
stricter and faster, validator.

However, the strictness can be a burden in other packages;
for example, swh-storage tests rely on it to insert dummy data that raises
exception when accessed, and it would be hard to do while using the exact
expected type.

This commit reverts the strict behavior, but keeps the performance
optimization, by always checking with type equality, but in case type
equality fails (which would raise an error before this commit), it gives
the value a 'second chance', by trying isinstance.

This means that, outside tests, isinstance should not be used at all,
or very rarely.

Update to upstream version '3.0.0'
with Debian dir bb9cc036ee04c90a51f9c99a8ecabec167da2dc1