Keep NVARCHAR(MAX) length as -1

[kitloong]

Q	A
Type	bug
Fixed issues	#6038

Summary

As described in the mentioned issue, -0.5 from -1 / 2 will raise type error when trying to setLength

Argument #1 ($length) must be of type ?int, float given

dbal/src/Schema/Column.php

Line 78 in 8bc0d9a

public function setLength(?int $length): self

This PR check if length is -1 and keep it as is before perform division.

[derrabus]

Thank you.