Include Copyright information in the NuGet feed

At present it isn't obvious what the copyright is from the NuGet feed. Although the LICENCE contains a Copyright, that isn't easily discoverable programmatically from the nuget package. The Authors setting isn't sufficient.
It should be fairly simple to include a Copyright setting in the Bogus.csproj.

Open Bogus.csproj and inspect the existing package metadata, including the Authors setting. Add the requested copyright metadata and verify that it is discoverable in the generated NuGet package.

Written by the indexing model from the issue text.