6 files declare their use of ImagickConst in Imagick 8

Blur.php in src/Plugin/ImageToolkit/Operation/imagick/Blur.php

BlurImageEffect.php in src/Plugin/ImageEffect/BlurImageEffect.php

CompositeImageEffect.php in src/Plugin/ImageEffect/CompositeImageEffect.php

Convert.php in src/Plugin/ImageToolkit/Operation/imagick/Convert.php

ConvertImageEffect.php in src/Plugin/ImageEffect/ConvertImageEffect.php

ImagickToolkit.php in src/Plugin/ImageToolkit/ImagickToolkit.php