binary-search: no-op declare compliance with 1.2.0
binary-search: no-op declare compliance with 1.2.0

JSON now uses error object to indicate "not in array" rather than -1.

Rust has and will continue to translate this to `None`; no action
needed.

https://github.com/exercism/problem-specifications/pull/1338

petertseng/exercism-rust,exercism/xrust,exercism/xrust,petertseng/exercism-rust,petertseng/exercism-rust