Add GitHub actions to ZigbeeNet

[JanneMattila]

Here's first take on the GitHub Actions implementation to ZigbeeNet. In case process does not make sense then please provide feedback and I'll change it.

Maybe notable difference would be using tag name from GitHub Release for versioning of the NuGet packages. And those would share the versioning between packages. That can be of course skipped and use only versioning from the .csproj but of course you would have to increment them manually always.

This setup has been put into here for reference for easier review and validation.

[Mr-Markus]

Hi @JanneMattila

thanks for your PR. I merge it into develop and master, removed appvayor and added $NUGET_API_KEY variable. CI is working, but CD not.
Could you please check what's wrong in https://github.com/Mr-Markus/ZigbeeNet/actions/runs/1158384590 please?
I don't understand how it's working, yet but hope I will do it if it's running

[JanneMattila]

Sure. Let me check and update you.

[JanneMattila]

It's expecting release version tag to start with v e.g., v1.5.0 and strips out that start character. Could you try with that? Error messages are visible under Actions menu and then CD.