Update custom_password_authenticator.rst

Fixed TokenInterface use statement causing compile errors
bug #3435 Update custom_password_authenticator.rst (boardyuk)

This PR was merged into the 2.4 branch.

Discussion
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Update custom_password_authenticator.rst

Fixed TokenInterface use statement which was causing a "FatalErrorException: Compile Error:" to occur

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4101d9b Update custom_password_authenticator.rst