v3.0.0a0

This is an alpha release for developers. Do not use in production but feel free to test and provide feedback.

See #486

Main changes at this point are:

• No plugins
• There is an entrypoint you can use to register connection plugins. For instance, using poetry you could do the following:

[tool.poetry.plugins."nornir.plugins.connections"]
"nornir_napalm.napalm" = "nornir_napalm.connections:Napalm"

See https://github.com/nornir-automation/nornir_napalm as an example of a plugin supporting nornir 3.0.0