Linter: Add @salihgueler to AUTHORS

[pq]

Attribution for https://github.com/dart-lang/linter/pull/2672.

@salihgueler: how would you like to be credited in https://github.com/dart-lang/linter/blob/master/AUTHORS ?

Thanks again for the fix!

[salihgueler]

Hi @pq Thank you for this :) I would like to be added as

Muhammed Salih Guler <[email protected]>

Do you want me to create a PR for that? :)

[pq]

No worries!

https://github.com/dart-lang/linter/pull/2679

[pq]

(And again, thanks for the fix!)