chore: add empty requests constant

crates/eips/src/eip7685.rs

@@ -3,9 +3,15 @@
 //! [EIP-7685]: https://eips.ethereum.org/EIPS/eip-7685
 
 use alloc::vec::Vec;
-use alloy_primitives::Bytes;
+use alloy_primitives::{b256, Bytes, B256};
 use derive_more::{Deref, DerefMut, From, IntoIterator};
 
+/// The empty requests hash.
+///
+/// This is equivalent to `sha256(sha256(0) ++ sha256(1) ++ sha256(2))`
+pub const EMPTY_REQUESTS_HASH: B256 =
+    b256!("6036c41849da9c076ed79654d434017387a88fb833c2856b32e18218b3341c5f");
+
 /// A list of opaque EIP-7685 requests.
 #[derive(Debug, Clone, PartialEq, Eq, Default, Hash, Deref, DerefMut, From, IntoIterator)]
 #[cfg_attr(any(test, feature = "arbitrary"), derive(arbitrary::Arbitrary))]