Seperating setting up the token and creating the manager

[Rafnuss]

I believe that it's best practice to seperate the two to avoid hard coding and code sharing of token. Something like this would be great:

keyring::key_set_with_value(
  service = "ZENODO_PAT",   # Service name (matches the environment variable)
  password = "<your_token>" # Replace with your actual Zenodo token
)

zenodo <- ZenodoManager$new(
  token = keyring::key_get(service = "ZENODO_PAT"), # Use this as default value
  logger = "INFO"
)

See https://github.com/bluegreen-labs/ecmwfr/blob/master/R/wf_set_key.R for instance.