Fix incorrect use of syn::exports (#7838)

* Fix incorrect use of syn::exports

Instead of using `syn::exports` we should import the trait from the
quote crate directly.

* Use own macro for test cases to fix compilation with latest syn

* Fix test

substrate/test-utils/derive/Cargo.toml

@@ -10,7 +10,7 @@ description = "Substrate test utilities macros"
 
 [dependencies]
 quote = "1.0.6"
-syn = { version = "1.0.33", features = ["full"] }
+syn = { version = "1.0.58", features = ["full"] }
 proc-macro-crate = "0.1.4"
 
 [lib]