Update action to run on node 16

[xt0rted]

Node 12 is deprecated so this needs to updated to node16 and a new major version released.

[AnthonySteele-NewDay]

Any update? Most of the issues here are caused by this project not tracking changes to dotnet format commandline options.
Currently it's not obvious that this action is unusable with any supported version of .NET (version 6 or 7 as of January 2023), would be better if that's resolved one way or the other to clear up confusion.