[WhiteAbeLincoln]

Change summary

Ensures the version update notice is written to stderr instead of stdout, which can corrupt machine readable / pipeable commands like fastly auth token.

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New Feature Submissions:

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Changes to Core Features:

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User Impact

Users on older versions of the cli can use commands like FASTLY_AUTH_KEY="$(fastly auth token)" ...

Are there any considerations that need to be addressed for release?