Remove unused commitment fn (#1511)

solidity/contracts/libs/MultisigIsmMetadata.sol

@@ -137,21 +137,6 @@ library MultisigIsmMetadata {
         return _metadata[_validatorsOffset(_metadata):];
     }
 
-    /**
-     * @notice Returns the size of the validator set encoded in the metadata
-     * @dev Validator addresses are encoded as tightly packed array of bytes32,
-     * sorted to match the enumerable set stored by the module.
-     * @param _metadata ABI encoded Multisig ISM metadata.
-     * @return The size of the validator set encoded in the metadata
-     */
-    function commitment(bytes calldata _metadata)
-        internal
-        pure
-        returns (uint256)
-    {
-        return (_metadata.length - _validatorsOffset(_metadata)) / 32;
-    }
-
     /**
      * @notice Returns the size of the validator set encoded in the metadata
      * @dev Validator addresses are encoded as tightly packed array of bytes32,