v0.7.0 - enforce nullable type declaration for default null values

Before:

<?php

class NullableTypeForDefaultNull
{
    public function getNameLabel(string $name, string $title = null): string
    {
        $label = $name;
        if ($title !== null) {
            $label .= " " . $title;
        }

        return $label;
    }
}

After:

<?php

declare(strict_types=1);

class NullableTypeForDefaultNull
{
    public function getNameLabel(string $name, ?string $title = null): string
    {
        $label = $name;
        if ($title !== null) {
            $label .= " " . $title;
        }

        return $label;
    }
}