Scripty.MsBuild settings encoding problem

[ossiv]

We are seeing this problem in some of our projects:

Scripty.MsBuild.targets(31,5): Newtonsoft.Json.JsonReaderException: Unexpected character encountered while parsing value: �. Path '', line 0, position 0.

So far we've only seen this when building on Windows. It seems to be caused by the msbuild task passing settings to the Scripty process as JSON, and the process then failing to parse them.