Is your feature request related to a problem? Please describe.
Currently i get an exception:

System.TypeLoadException : Method 'get_Description' in type 'Snapper.Nunit.EqualToSnapshotConstraint' from assembly 'Snapper.Nunit, Version=2.0.0.0, Culture=neutral, PublicKeyToken=c90abed6faf59688' does not have an implementation.

Describe the solution you'd like
Support NUnit v4

Describe alternatives you've considered
No alternate beside to drop this library

Additional context
none