STALEBOT: Update to stale out issues after one year

[keithhackbarth]

In order to better triage issues, it would be helpful to clear out old issues. I used 365 as it seems to be the commonly used configuration for other open-source projects. Example: https://github.com/integrations/slack/blob/master/.github/stale.yml

[ulgens]

Considering how often this repo gets love from its maintainers, I wouldn't recommend closing issues just because they are old. As far as I can see, most of them are still relevant.

[erikwrede]

Closing this for cleanup. Agree with @ulgens, open issues should remain open for users to identity problems they occur. Especially when there's no active maintainers to consult, stale bot would add more confusion.