monero-oxide officially tracks the latest stable Rust version there's merit to
track. Where possible, std-shims (primarily used to provide alternatives to
members of std on no-std environments) may provide polyfills so
monero-oxide may use modern features without actually bumping its MSRV.
Any polyfills provided by std-shims are not recommended for usage. They will
presumably be much more inefficient and will receive a fraction of the testing.
Only the targeted Rust version is officially supported.