Relax version of os_str_bytes

[jerome-pouiller]

os_str_bytes 6.0 now depends on Rust 1.52.

clap_lex depends on os_str_bytes 6.0 but, it seems that version 4.0 is sufficient.

It matters because the version of rustc provided by the last Debian (and the last RaspbianOS) is 1.48.0. Do you think you could relax the dependency of os_str_bytes in '>= 4.0, < 7.0' ?

[epage]

Our official MSRV policy is "two versions back" though we've been letting it go a little (1) as an experimental policy of "6 months back" and (2) out of laziness. There are newer features we want to be using that I do not see us holding back for once we can.

Even if we loosened the version requirement for os_str_bytes, clap itself is using features from 1.52. See #3267 for more of a discussion on this.