Pymyob

51 Added endpoint for Sale/CustomerPayment (thanks theducvu!).

c4c47ae9ede704429894a39896690bd1478ac950 Added support for custom oauth state parameter.

2063d7112e03b017f1da7d233d8dd473cb67c206 Fixed a bug introduced in 1.2.8 (47).

47 Added a check to ensure the oauth state being passed to the `PartnerCredentials` class has properly hydrated datetimes, to avoid getting errors when checking expiry.
0b2ac725dbc810f2ee7fe90af7d1cba8e5f9178e Added a `DATETIME_FORMATS` constant, which can be be imported and used by developers to parse MYOB datetimes that come through in the payloads (pymyob does not currently perform any postprocessing on the response payloads returned from the MYOB api).

Repo maintenance:
43 Updated tests/linting to GH actions.
44 Bumped to isort5.
7772f9d5ab19ee11c519a1208f62c4156e75d35a Added a vanity badge.

6046389c1da6c9e393e3d0be52bdddb6f330a277 Added `MyobRateLimitExceeded` exception for 403 responses that have come about as a result of ratelimiting. This is thus a subclass of `MyobForbidden`, which is the exception that was being raised previously.

41 Added endpoint for `Inventory/Location` (thanks theducvu!).