Update to upstream version '6.8.0'
with Debian dir 877b4f10a809928e9ad63b634752f78ae1d626f1

This separate package was introduced recently and is needed for our CLIs
to pass type checking.

This allows using the "system" tox, if it's recent enough, instead of
always provisioning an internal .tox venv with tox 4.

Instead of going back to py3, pass through the environment name, so that
it can be called with an arbitrary interpreter version.

When parsing the configuration, tox would complain about the unfollowed
line continuation (which is what happens when the testenv was qualified
with neither full nor minimal).

Moving {posargs} to be unqualified allows the line continuation
character to always have something behind it.

Update to upstream version '6.7.0'
with Debian dir 8213f89ad4e31b5223fc869c1a7da015e482b5b4

This adds several helper methods returning SWHIDs to model objects,
namely:

- SkippedContent.swhid()
- DirectoryEntry.swhid()
- SnapshotBranch.swhid()
- Release.target_swhid()
- Revision.directory_swhid() and Release.parent_swhids()
- OriginVisitStatus.origin_swhid() and
  OriginVisitStatus.snapshot_swhid()

Better using latest mypy release.

Update to upstream version '6.6.3'
with Debian dir 31fdf17d4194de4add0cf4ae2de37d1595575405

Related to swh/meta#4960

See: https://tox.wiki/en/latest/upgrading.html#updating-usage-with-e

Related to swh/meta#4959

Update to upstream version '6.6.2'
with Debian dir e5c2f227d7e6087b3152d6160e9502f4199a6105

Previously when looking up data by key in an ImmutableDict, the inner
tuple storing keys and values was iterated until finding the requested
key.

This is not really efficient when the ImmutableDict contains a lot of
entries, typically for an origin snapshot containing a lot of branches.

So use an inner dictionary to speedup look up by key operations and
improve loader performances.

This fixes python 3.7 support due to poetry, a dependency of isort, that
removed support for that Python version in a recent release.

In order to remove warnings about /apidoc/*.rst files being included
multiple times in toc when building full swh documentation, prefer to
include module indices only when building standalone package documentation.

Also include them the proper sphinx way.

Related to T4496

Update to upstream version '6.6.1'
with Debian dir 5264b8650def64f97ea2b7aae15cadc2dc496623