fix(windows): rustc false positives in tests

For detailed explanation of this issue see d6ee81b6f911d21023750e2cb9f6d7eff44bf379

Refs: d6ee81b6f911d21023750e2cb9f6d7eff44bf379

Signed-off-by: Christina Sørensen <ces@fem.gg>

src/output/render/links.rs

@@ -45,6 +45,7 @@ pub mod test {
     use nu_ansi_term::Color::*;
     use nu_ansi_term::Style;
 
+    #[allow(dead_code)]
     struct TestColours;
 
     impl Colours for TestColours {