fix color space for tinted grayscale textures in generated items

Author: KurtThiemann

src/Model/GeneratedItem.php

@@ -96,6 +96,10 @@ public function render(int $width, int $height, ?TinterList $tinters = null): Im
             foreach ($layers as $i => $layer) {
                 $image = clone $layer->getImage($tick);
 
+                if ($image->getImageType() !== Imagick::IMGTYPE_TRUECOLORMATTE) {
+                    $image->transformImageColorspace(Imagick::COLORSPACE_UNDEFINED);
+                }
+
                 if ($tinters !== null) {
                     $color = $tinters->getTintColor($i);
                     if ($color !== null) {