maint: Add version bound to new additions

rust/nix-bindings-store/src/derivation.rs

@@ -1,7 +1,11 @@
+#![cfg(nix_at_least = "2.33")]
+
 use nix_bindings_bindgen_raw as raw;
 use std::ptr::NonNull;
 
 /// A Nix derivation
+///
+/// **Requires Nix 2.33 or later.**
 pub struct Derivation {
     pub(crate) inner: NonNull<raw::derivation>,
 }