feat(natu): ignore imported let bindings

src/natu/rules/single_use_binding.rs

@@ -38,7 +38,8 @@ fn is_single_use(graph: &ScopeGraph, let_scope: &LetScope, binding: &Binding) ->
         .filter(|reference| graph.resolve(**reference).contains(&binding.declaration))
         .collect::<Vec<_>>();
 
-    self_references == 0
+    !binding.is_import
+        && self_references == 0
         && external_references.len() == 1
         && (binding.is_lambda
             || !graph.crosses_lambda_scope(*external_references[0], binding.declaration))