fix: escape reserved keyword 'gen' in test helper function

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

src/tests/common/test_helpers.rs

@@ -188,7 +188,7 @@ pub fn create_nested_temp_dir_structure(dir: &TempDir) -> (PathBuf, PathBuf, Pat
 pub fn create_temp_file_with_random_binary_content(dir: &TempDir, filename: &str, size: usize) -> PathBuf {
     use rand::Rng;
     let mut rng = rand::thread_rng();
-    let random_data: Vec<u8> = (0..size).map(|_| rng.gen::<u8>()).collect();
+    let random_data: Vec<u8> = (0..size).map(|_| rng.r#gen::<u8>()).collect();
     create_temp_file_with_binary_content(dir, filename, &random_data)
 }