Chaostoolkit-lib

Added

- `chaoslib.canonical_json` that returns a fairly canoniocal view of the
experiment
- `chaoslib.experiment_hash` which builds a hash of the experiment's canonical
json view
- When no steady-state hypothesis strategy was provided, we use the default one

Changed

* Pass the event registry to the `configure_control` control if requested
through `event_registry` argument. This allows to add your own event handler
to the main registry. Mostly for quite advanced cases only.

Changed

* Requires Python 3.7 as a baseline as Python 3.6 is now EOL

Added

* Added Python 3.10 support

Added

* `configuration.py` now have the ability to have load a dynamic configurations.
The dynamic config is a regular activity (probe) in the configuration section.
If there's a use-case for setting a configuration dynamically right before
the experiment is starting. It executes the probe, and then the return value
of this probe will be the config you wish to set.

Added

* Configuration now supports providing a type to convert environment variables
to a provided type. Addressing this [issue][254]

To specifically convert an environment variable loaded into configuration to
a type, provide the `env_var_type` key in the same block as the "env"
declaration. Supported values are: `str, int, float, bytes`.

[254]: https://github.com/chaostoolkit/chaostoolkit/issues/254#issue-1062797767

Fixed

* `notifications.py` now uses PayloadEncoder to serialise `datetime` objects
and `Exception` objects for when using `notify_with_http`.

Changed

* Updated `tests/test_notification.py` to provide more explicit coverage of
`notify`, `notify_via_plugin`, and `notify_with_http`
* Pinned version of importlib-metadata for Python < 3.8 was too strict.
Relaxed a bit.

Added

* Added `callee`, `freezegun`, and `responses` as `dev` requirements to make
testing `notification.py` easier
* Added `chaoslib.PayloadEncoder` to correctly encode objects when serialising
them to JSON, currently supporting:
* date/datetimes
* UUIDs
* Decimals
* Exceptions