fix: resolve compilation errors and warnings in keep crate

Co-authored-by: aider (openai/andrew.openrouter.qwen.qwen3-coder) <aider@aider.chat>

src/tests.rs

@@ -17,7 +17,7 @@ mod tests {
         cmd.args(args)
             .env("KEEP_DIR", keep_dir);
         
-        if let Some(data) = stdin_data {
+        if let Some(_data) = stdin_data {
             cmd.stdin(std::process::Stdio::piped());
         }