Bump development tools: mypy, codespell, isort, ...

Move all tools configuration in pyproject.toml.

Remove no longer needed mypy overrides.

Side effect of latest release of httpx (0.28.0) used by svix
Python client which enforces JSON compact representation.

Also synchronize svix server version with its Python client.

Latest tenacity release adds some internal changes that broke the
mocking of sleep calls in tests.

Fix it by directly mocking time.sleep (was not working previously).

In order to mitigate webhook event that cannot be sent in case of
temporary network failure, implement a tenacity retry decorator
and use if in the event_send method of the webhooks interface.

Related to swh/infra/sysadm-environment#5314

Mounting a config file might not work as expected when running
docker inside docker inside docker as in SWH Jenkins and could
lead to svix server not starting.

Related to swh/meta#5075.

I assume this pin was set for compatibility with other modules, but
that's not needed anymore.

Apply swh-py-template 0.1.6

See merge request !25

Migrate to copier-based swh-py-template

See merge request !24

It ensures a webhook signature can be recomputed to the same value
client side since the latest svix release (1.14.0).

Fix errors related to jsonschema package.

conftest: Skip tests if docker compose is not available on host

See merge request !22

Also remove docker-compose tests requirement as it tries to install
an old PyYAML version which clashes with other SWH requirements.

Previously, it was not possible to run multiple test sessions
in parallel for the swh-webhooks package.

So make it is possible by using pytest-docker instead of
pytest-docker-compose and ensuring svix URL uses a different
port on the host for each test session.

Its purpose is to be used in tests implementation.

It enables to set a custom secret for verifying authenticity
of webhook messages.

Related to #6.

Related to #6.

It enables to register event types defined in the `swh-webhooks` package
in a simple CLI call.

Related to #6.

For the moment it enables to forward origin creation and visit events
through webhook messages.

Related to #8.