Changed authentication link log level

[CameronDevine]

Changed authentication link logging statements to warn from debug so they will not be missed if the log level has not been increased.

When I was trying to get the O365Modern mode working I was confused because I couldn't find the link that the document specifies should exist in the logs to complete the login process. I eventually figured out that I needed to increase the log level, but that took a while. To help others in the future I believe the URL should be visible at a lower log level.

[jdchristensen]

For future readers of this PR, note that the level was changed from debug to warn, not the other way around. Maybe @CameronDevine can edit the original message to correct this.

[CameronDevine]

@jdchristensen rereading my original pull request message I believe it is correct.

[jdchristensen]

@CameronDevine Sorry, you're right, I just misread it.

[CameronDevine]

@jdchristensen no problem

[esabol]

I think @mguessan committed this change, so it should be in the most recently released version (6.2.1). Please confirm and then close this issue if so, @CameronDevine.