we get errors decoding vp9+yuv444 frames, so disable it

git-svn-id: https://xpra.org/svn/Xpra/trunk@8943 3bb7dfac-3a0b-4e04-842a-767bc560f471

src/xpra/codecs/dec_avcodec2/decoder.pyx

@@ -179,7 +179,7 @@ def get_input_colorspaces(encoding):
     assert encoding=="vp9"
     #we only handle YUV420P encoding at present,
     #but we ought to be able to support the other YUV modes out of the box already:
-    return ["YUV420P", "YUV422P", "YUV444P"]
+    return ["YUV420P"]
 
 def get_output_colorspace(encoding, csc):
     if encoding not in CODECS: