Use cargo_bin!() macro instead of deprecated cargo_bin fn in integration tests

[MsfPablo]

Closes #1178.

The integration-test helper cmd() used Command::cargo_bin(env!("CARGO_PKG_NAME")).unwrap(), which relies on assert_cmd probing the target/ layout. As tracked in #1178, that path is fragile under non-default build directories (e.g. CARGO_BUILD_BUILD_DIR) and the cargo_bin function has been deprecated in favor of the cargo_bin! / cargo_bin_cmd! macros.

This switches the helper to:

fn cmd() -> Command {
    Command::new(assert_cmd::cargo_bin!())
}

cargo_bin!() resolves the binary through the official CARGO_BIN_EXE_lsd env var that Cargo sets for the package's own bin target, so it is robust to the build directory and no longer needs an .unwrap().

Dependency change

cargo_bin!() landed in assert_cmd 2.0.17, so this bumps the assert_cmd dev-dependency in the lockfile from 2.0.14 → 2.2.2. The Cargo.toml constraint stays at assert_cmd = "2" (no tightening); this is a lockfile-only update.

Verification

• cargo build --tests — clean
• cargo test — 42 passed; the only failure (test_date_custom_format_supports_nanos_with_length) is pre-existing and locale-dependent (%.3f emits a comma under LC_TIME=es_ES.UTF-8\)); it fails identically on clean mainand passes under theen_US`/C locale used in CI.
• cargo fmt --check — clean
• cargo clippy --all-targets — no new warnings (the remaining ones are pre-existing in src/display.rs)

[MsfPablo]

Ping on this. It's a mechanical swap to the cargo_bin!() macro, so it should be quick to eyeball. Let me know if you'd rather fold it into a broader test cleanup instead.