Minor changes

[Pathoschild]

This pull request makes a few minor changes:

• Migrated to the new NuGet package reference format.
• Updated the mod build config package.
• Removed code which has no effect.
• Standardised the version format to avoid issues for non-SMAPI tools which read manifests.

These are just internal changes, there's no need to deploy a new version. :)

[Pathoschild]

This is included in pull request #2.