fix(deps): update rust crate darling to 0.21.0 (#104)

renovate[bot] · web-flow · commit 9751eff032b0 · 2025-09-27T10:55:29.000+08:00
Co-authored-by: renovate[bot] &lt;29139614+renovate[bot]@users.noreply.github.com&gt;
diff --git a/spec/Cargo.toml b/spec/Cargo.toml
@@ -9,6 +9,6 @@ path = "src/lib.rs"
 proc-macro = true
 
 [dependencies]
-darling = "0.20.8"
+darling = "0.21.0"
 syn = "2.0.103" # needed for `darling`
 
