fix: change windows-only imports to be windows-only

Apparently this line is required for the Windows build, but leads to warnings on systems that build the eza port with a port of rust 1.77.2, which at this time seems to be limited to the BSDs.

Signed-off-by: Volker Schlecht <47375452+VlkrS@users.noreply.github.com>

src/output/mod.rs

@@ -1,5 +1,4 @@
-#[cfg_attr(target_os = "netbsd", allow(unused_imports))]
-#[cfg_attr(target_os = "freebsd", allow(unused_imports))]
+#[cfg(target_os = "windows")]
 pub use self::cell::{DisplayWidth, TextCell, TextCellContents};
 pub use self::escape::escape;