fix: compile on older compilers

sdgb-cli/Cargo.toml

@@ -29,3 +29,4 @@ nyquest-preset = { version = "0.2.0", features = ["async"] }
 palc = { version = "0.0.1", features = ["derive"] }
 futures-util = { version = "0.3.31", optional = true }
 ctrlc = { version = "3.4.7", features = ["termination"] }
+rustversion = "1.0.21"

sdgb-cli/src/main.rs

@@ -220,7 +220,12 @@ async fn main() -> Result<(), Box<dyn snafu::Error>> {
                 .truncate(true)
                 .write(true)
                 .open("players.json")?;
-            file.lock()?;
+
+            #[rustversion::since(1.89)]
+            {
+                file.lock()?;
+            }
+
             let writer = BufWriter::new(file);
             serde_json::to_writer(writer, &user_ids)?;
             info!("dumped {} user id", user_ids.len());