Chaostoolkit-lib

Changed:

- When working with `jsonpath` tolerances and substitutions like `${myvalue}`
`chaostoolkit` now gives the user an error message with all substituted values when the
`expect` block does not match the output of the `probe`.
- Tolerance field can now be substitued with variables even when the tolerance
remains a native type. So this is now supported:

json
{
"configuration": {
"expected": 3
},
"steady-state-hypothesis": {
"title": "",
"probes": [
{
"name": "check-stuff",
"type": "probe",
"tolerance": "${expected}",
"provider": {
"type": "python",
"module": "statistics",
"func": "mean",
"arguments": {
"data": [1, 3, 4, 4]
}
}
}
]
}
}

Changed

- Dropped `chardet` and `cchardet` (optionals dependencies) in favour to the
faster and friendly-licenced
[charset-normalizer](https://pypi.org/project/charset-normalizer/) which will
be installed by default
- Removed `simplejson` support entirely as this library doesn't seem to be
much updated anymore. Sticking with stdlib `json` and maybe one day we'll
byte the bullet and migrate to `orjson`
- Fix different behaviors in checking status from steady-state in Python 3.7

Changed

- The http activity provider can now substitute its `timeout` field so it can
be read from the configuration
- The `expect` field of a `jsonpath` tolerance can now be substituted with
configuration values [267][267]
- Substitution of list of lists now returns a list of lists instead of
flattening

[267]: https://github.com/chaostoolkit/chaostoolkit-lib/issues/267

Added

- A new `"skip"` strategy to explicitely dismiss the hypothesis entirely
- A log message when an activity is in dry mode
- Bump dependencies

Changed

- When trying to substitute a single value in an argument but that value isn't
actually a variable, but instead a string to pass as-is to the function
of the activity, we failed with a `KeyError` because we were looking into
the configuration/secrets for a key that was not meant to be there. Now,
we properly handle this case and leave the string as it should be. This case
may easily happen for `process` activities where you make a reference to
an environment variable when the process is executed. For instance:

json
"provider": {
"type": "process",
"path": "cat",
"arguments": "$MY_FILE"
},


Here `"$MY_FILE"` is not a pattern for chaos toolkit to replace with a value,
it's a literal string to be passed to the `cat` command.

Changed

- Allow for missing environment variable when `default` property is set, even
to a `None` value