Breaking API change in DiffSync 1.4.0

[glennmatthews]

Environment

• DiffSync version: 1.4.0
• Python version: any

Observed Behavior

#90 introduced a breaking API change in that DiffElement.action changed from a string value to an enum value. This impacts projects such as network-importer (networktocode/network-importer#256) and any other project that is relying on the value of DiffElement.action, such as to implement custom Diff ordering based on the action.

In the short term it may be simplest just to revert the entirety of #90 and cut a new DiffSync release.

Expected Behavior

API to remain stable in minor and patch releases.

Steps to Reproduce

1. See for example invalid DiffElement - just fresh install of network-importer-3.0.3 network-importer#256