[jhbuild] world: pycairo has dropped Python 2 support in git master

[Christoph Reiter <creiter src gnome org>]

commit a508fdbb55ea80d896a072bab969d38f746a4f4b
Author: Christoph Reiter <creiter src gnome org>
Date:   Thu Jan 23 22:14:36 2020 +0100

    world: pycairo has dropped Python 2 support in git master
    
    Track the last branch supporting Python 2 instead.

 modulesets/gnome-world.modules | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/modulesets/gnome-world.modules b/modulesets/gnome-world.modules
index c6fd7ed6..206e46cb 100644
--- a/modulesets/gnome-world.modules
+++ b/modulesets/gnome-world.modules
@@ -701,6 +701,7 @@
 
   <distutils id="pycairo-python2">
     <branch repo="github.com" module="pygobject/pycairo.git"
+            revision="pycairo-1.18"
             checkoutdir="pycairo-python2"/>
   </distutils>