libX11: Update version from 1.6.6 to 1.6.7

Change-log from the announcement:

> Bhavi Dhingra (1):
>      XcmsLookupColor: fully initialize XColor structs passed to _XColor_to_XcmsRGB
>
> Matt Turner (1):
>      libX11 1.6.7
>
> Michel Dänzer (2):
>      poll_for_response: Call poll_for_event again if xcb_poll_for_reply fails
>      poll_for_event: Allow using xcb_poll_for_queued_event

libX11.be0

@@ -1,6 +1,6 @@
 #!/usr/bin/env beesh
 
-# BEE_VERSION libX11-1.6.6-0
+# BEE_VERSION libX11-1.6.7-0
 
 ## this file was created by bee init and should be executed to build a
 ## bee-package. (Additional hints are located at the end of this file.)

scripts/update-graphics-and-x-stack.sh

@@ -31,3 +31,4 @@ sudo bee install -f nvidia_linux-4.14.74-227-390.87-0
 sudo bee update mesalib-18.2.1-0
 sudo bee update wayland-1.16.0-0
 sudo bee update libdrm-2.4.94-0
+sudo bee update libX11-1.6.7-0