Remove warning message when username and password aren't used

[tremblaysimon]

Context

Related to PR #60 (thank you for that by the way!) that add the possibility to use a smtp server without authentication when using a self-hosted runner. We can see a warning message here when using the action in the log output:

and also in the Annotations section of the workflow run summary:

Warning message:
Username and password not specified. You should only do this if you are using a self-hosted runner to access an on-premise mail server.

Problem

Normally, a warning message indicates something that should be fixed. Here there is nothing to fix since it's ok to use in certain condition a smtp server without authentication (when using self-hosted runner for example). In the end the user who uses the action will be tricked by the warning message since there is nothing to do to fix that.

Solution

Remove that warning message.

What do you think?

[dawidd6]

Guess it's fine.