Fix clippy unexpected_cfgs warning with recent nightly

CHANGELOG.md

@@ -23,6 +23,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
  - Fix `compute_encoded_size()` for `BitroundCodec` incorrectly indicating various data types were unsupported
  - Fix a link in chunk grid docs
  - Fix incorrect minimum dependency versions and add CI check
+ - Fix clippy `unexpected_cfgs` warning with recent nightly
 
 ## [0.13.0] - 2024-04-20
 

build.rs

@@ -1,7 +1,10 @@
 #[rustversion::nightly]
 fn main() {
+    println!("cargo:rustc-check-cfg=cfg(nightly)");
     println!("cargo:rustc-cfg=nightly");
 }
 
 #[rustversion::not(nightly)]
-fn main() {}
+fn main() {
+    println!("cargo:rustc-check-cfg=cfg(nightly)");
+}