fix(deps): update rust crate syn to v2

Author: renovate[bot]

macro/Cargo.toml

@@ -6,7 +6,7 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-syn = "1.0.107"
+syn = "2.0.59"
 quote = "1.0.23"
 struct_indexer_core = { path = "../core" }