Use modulo instead of and operation to validate the proof size

[mininny]

Description

The slow implementation loads the _proof length from calldata and checks that this length is a multiple of 60.

However, this check uses a logical AND which may lead to accepting invalid values that are not multiple of 60.

	if and(b32asBEWord(calldataload(shortToU64(uint16(stateContentOffset)+paddedStateSize))), shortToU256(60-1)) != (U256{}) {

Moreover, the check is insufficient. _proof is expected to be a multiple of 60 * 32, however only the fact that it is a multiple of 60 is checked.

The logical AND check should be replaced with a modulo operation to ensure that it is a multiple of 32 * 60.