Set up Nuget deploy pipeline

[zeusongit]

Introduced a nuspec file and nuget.config for packaging DynamoVisualProgramming.PythonEngine.PythonNet3.
Updated pipeline.yml to support NuGet deployment.

I don't see a better way of doing it with CI, so that the Nuget and Dynamo package version match the binary version, but we will have to update Directory.build.props file each time before deploying a new version. Hopefully we won't have to do it often.

[Copilot]

Pull Request Overview

This PR establishes a NuGet deployment pipeline for DynamoVisualProgramming.PythonEngine.PythonNet3 alongside the existing Dynamo Package Manager deployment. The changes introduce NuGet packaging configuration files and update the CI/CD pipeline to support automated NuGet publishing.

Key changes:

• Added NuGet package specification and configuration files
• Updated CI/CD pipeline to include NuGet deployment with API key credential handling
• Bumped version numbers across pipeline and build configuration files

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
pipeline.yml	Added NuGet deployment configuration with credentials and package settings
nuget.config	Defined NuGet package source pointing to the public NuGet repository
DynamoVisualProgramming.PythonEngine.PythonNet3.nuspec	Specified NuGet package metadata and file inclusions for the PythonNet3 engine
README.md	Documented the new NuGet deployment process and version management requirement
Directory.Build.props	Updated copyright year and version prefix to align with new release

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[twastvedt]

I think you should be able to follow the pattern used by Player:

<MS_PACKAGE_VERSION Condition="'$(MS_PACKAGE_VERSION)' == ''">0.0.0.0</MS_PACKAGE_VERSION>
<VersionPrefix>$(MS_PACKAGE_VERSION)</VersionPrefix>