update CHANGELOG.md

Author: Muhammad-Altabba

packages/web3-eth-abi/CHANGELOG.md

@@ -182,4 +182,7 @@ Documentation:
 
 -   fix encodedata in EIP-712 (#7095)
 
-## [Unreleased]
+## [Unreleased]
+
+### Added
+-   Handle common cases for smart contract errors according to EIP 838: `0x4e487b71` which is the ‘selector’ for `Panic(uint256)` and `0x08c379a0` is the ‘selector’ of `Error(string)`. (7155)