address review: revert return None -> Some(Self::Unknown) change

Per ntBre's feedback, the else branch should remain `return None`
as in the original code.

Author: User

crates/ruff_linter/src/rules/fastapi/rules/fastapi_unused_path_parameter.rs

@@ -411,8 +411,7 @@ impl<'a> Dependency<'a> {
                 .map(|param| param.name().as_str())
                 .collect()
         } else {
-            // No matching method found — treat as unknown to suppress false positives.
-            return Some(Self::Unknown);
+            return None;
         };
 
         Some(Self::Class(parameter_names))