should not auto fix when configured to warn

[runspired]

Was surprised to find that setting this to warn still results in auto fix, unfortunately that makes this library unusable when a disable directive is being used for an autogenerated file that may not always be present.

[bmish]

This is out of the rule's control. ESLint rules aren't aware of whether the user enables them with warn or error severity. And the autofixer can be used anytime the rule is enabled regardless of severity.