Cargo.toml: dedup feat_require_unix_hostid dep

[oech3]

feat_os_macos depends on feat_os_unix which depends on feat_require_unix_hostid.

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/misc/io-errors. tests/misc/io-errors is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/tail/tail-n0f. tests/tail/tail-n0f is passing on 'main'. Maybe you have to rebase?
Skipping an intermittent issue tests/tail/inotify-dir-recreate (passes in this run but fails in the 'main' branch)
Note: The gnu test tests/dd/no-allocate is now being skipped but was previously passing.
Congrats! The gnu test tests/seq/seq-epipe is now passing!

[cakebaker]

Good catch, thanks!