Format the compile-test sources with rustfmt 0.8.2

test_suite/tests/compile-fail/unknown-attribute/container.rs

@@ -10,10 +10,10 @@
 extern crate serde_derive;
 
 #[derive(Serialize)]
-#[serde(abc="xyz")]
+#[serde(abc = "xyz")]
 //~^^ ERROR: unknown serde container attribute `abc`
 struct A {
     x: u32,
 }
 
-fn main() { }
+fn main() {}