Add another gm to Win Intel Vulkan blacklist

Bug: skia:6398
Change-Id: I3e4006ce1fbe1644c6d99467c5b9e785161dcc3d
Reviewed-on: https://skia-review.googlesource.com/19277
Commit-Queue: Greg Daniel <egdaniel@google.com>
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Reed <reed@google.com>
diff --git a/infra/bots/recipes/test.py b/infra/bots/recipes/test.py
index aceaf53..040c842 100644
--- a/infra/bots/recipes/test.py
+++ b/infra/bots/recipes/test.py
@@ -468,6 +468,7 @@
     blacklist(['vk', 'gm', '_', 'lcdtextsize'])
     blacklist(['vk', 'gm', '_', 'matriximagefilter'])
     blacklist(['vk', 'gm', '_', 'mixedtextblobsCOLR'])
+    blacklist(['vk', 'gm', '_', 'mixershader'])
     blacklist(['vk', 'gm', '_', 'pictureimagefilter'])
     blacklist(['vk', 'gm', '_', 'resizeimagefilter'])
     blacklist(['vk', 'gm', '_', 'rotate_imagefilter'])