remove 'guest' middleware to enable oauth account linking

[EkiciLP]

The guest middleware did not allow for authenticated users to call the /auth/oauth/redirect endpoint resulting in not being able to link an oauth account to yours.

[Boy132]

The redirect endpoint is not used for linking but for logging in.
Linking is https://github.com/pelican-dev/panel/blob/main/routes/base.php#L13-L14

For authenticated users it doesn't make sense to login again with oauth.

[EkiciLP]

Yes but the link endpoint currently just redirects to the oauth/redirect endpoint which would fail.

[Boy132]

It doesn't. The link endpoint redirects to the oauth provider page which then redirects back to the callback endpoint.
The redirect endpoint is only used for login.

[EkiciLP]

Ah sorry i swapped the redirect and callback endpoint in my head. The objective of this commit was for users to link their account without the frontend being done as they can't send get requests with a body using their browser.