make read_exact_into function unsafe

[kitcatier]

w3b/w3b-types-core/src/hex/convert.rs

Lines 242 to 249 in 8573b35

	pub fn read_exact_into(bytes: &[u8], hex: &mut String) {
	for byte in bytes {
	unsafe {
	hex.as_mut_vec().push(HEX_CHARS[(byte >> 4) as usize]);
	hex.as_mut_vec().push(HEX_CHARS[(byte & 0xf) as usize]);
	}
	}
	}

Hello, it is not a good choice to mark the entire function body as unsafe, which will make the caller ignore the safety requirements that the function parameters must guarantee, the developer who calls the read_exact_into function may not notice this safety requirement.
The unsafe function called needs to ensure that the parameter must be:

• This function is unsafe because the returned &mut Vec allows writing bytes which are not valid UTF-8. If this constraint is violated, using the original String after dropping the &mut Vec may violate memory safety, as the rest of the standard library assumes that Strings are valid UTF-8.
  https://doc.rust-lang.org/std/string/struct.String.html#method.as_mut_vec
  Marking them unsafe also means that callers must make sure they know what they're doing.