Feature-gate all uses of arbitrary (#8867)

Feature gate all uses of `arbitrary` so it is not compiled during release builds.


Co-Authored-By: Mac L <mjladson@pm.me>

crypto/kzg/Cargo.toml

@@ -7,10 +7,11 @@ edition = "2021"
 
 [features]
 default = []
+arbitrary = ["dep:arbitrary"]
 fake_crypto = []
 
 [dependencies]
-arbitrary = { workspace = true }
+arbitrary = { workspace = true, optional = true }
 c-kzg = { workspace = true }
 educe = { workspace = true }
 ethereum_hashing = { workspace = true }

crypto/kzg/src/kzg_commitment.rs

@@ -114,6 +114,7 @@ impl Debug for KzgCommitment {
     }
 }
 
+#[cfg(feature = "arbitrary")]
 impl arbitrary::Arbitrary<'_> for KzgCommitment {
     fn arbitrary(u: &mut arbitrary::Unstructured<'_>) -> arbitrary::Result<Self> {
         let mut bytes = [0u8; BYTES_PER_COMMITMENT];

crypto/kzg/src/kzg_proof.rs

@@ -110,6 +110,7 @@ impl Debug for KzgProof {
     }
 }
 
+#[cfg(feature = "arbitrary")]
 impl arbitrary::Arbitrary<'_> for KzgProof {
     fn arbitrary(u: &mut arbitrary::Unstructured<'_>) -> arbitrary::Result<Self> {
         let mut bytes = [0u8; BYTES_PER_PROOF];