we don't need unstable options

Author: RalfJung

ui_test/src/dependencies.rs

@@ -45,8 +45,7 @@ pub fn build_dependencies(config: &Config) -> Result<Dependencies> {
     setup_command(&mut build);
     build
         .arg("--target-dir=target/test_dependencies")
-        .arg("--message-format=json")
-        .arg("-Zunstable-options");
+        .arg("--message-format=json");
 
     let output = build.output()?;