chore(derive): update syn from 1 to 2 (#156)

Signed-off-by: Michael Zhalevich <[email protected]>

Author: cheshirskycode

derive-encode/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "prometheus-client-derive-encode"
-version = "0.4.1"
+version = "0.4.2"
 authors = ["Max Inden <[email protected]>"]
 edition = "2021"
 description = "Auxiliary crate to derive Encode trait from prometheus-client."
@@ -14,7 +14,7 @@ documentation = "https://docs.rs/prometheus-client-derive-text-encode"
 [dependencies]
 proc-macro2 = "1"
 quote = "1"
-syn = "1"
+syn = "2"
 
 [dev-dependencies]
 prometheus-client = { path = "../", features = ["protobuf"] }

derive-encode/src/lib.rs

@@ -25,7 +25,7 @@ pub fn derive_encode_label_set(input: TokenStream) -> TokenStream {
                     let attribute = f
                         .attrs
                         .iter()
-                        .find(|a| a.path.is_ident("prometheus"))
+                        .find(|a| a.path().is_ident("prometheus"))
                         .map(|a| a.parse_args::<syn::Ident>().unwrap().to_string());
                     let flatten = match attribute.as_deref() {
                         Some("flatten") => true,