attributes: remove unused syn's feature visit (#2530)

Remove unused `syn`s feature `visit`
; Conflicts:
;	tracing-attributes/Cargo.toml

Author: klensy

tracing-attributes/Cargo.toml

@@ -39,9 +39,9 @@ proc-macro = true
 async-await = []
 
 [dependencies]
-proc-macro2 = "1"
-syn = { version = "1.0.98", default-features = false, features = ["full", "parsing", "printing", "visit", "visit-mut", "clone-impls", "extra-traits", "proc-macro"] }
-quote = "1"
+proc-macro2 = "1.0.40"
+syn = { version = "1.0.98", default-features = false, features = ["full", "parsing", "printing", "visit-mut", "clone-impls", "extra-traits", "proc-macro"] }
+quote = "1.0.20"
 
 [dev-dependencies]
 tracing = { path = "../tracing", version = "0.1.35" }