[TypeDeclarationDocblocks] Use int key on inner array over mixed key on DocblockVarArrayFromPropertyDefaultsRector

[samsonasik]

Given the following code:

    private array $array = [
        'a' => [
            'b' => [
                ['c' => 'e', 'f' => 1],
                ['d' => 2],
            ],
        ],
    ];

It got diff:

+    /**
+     * @var array<string, array<string, array<mixed, array<string, string|int>>>>
+     */

mixed key should be int.

[samsonasik]

Fixed 🎉 /cc @TomasVotruba

[samsonasik]

All checks have passed 🎉 @TomasVotruba I am merging it ;)