Add UUID for 3.1.
diff --git a/Tools/msi/msi.py b/Tools/msi/msi.py
index a165770..92b8dcc 100644
--- a/Tools/msi/msi.py
+++ b/Tools/msi/msi.py
@@ -112,6 +112,7 @@
     "26":"{34ebecac-f046-4e1c-b0e3-9bac3cdaacfa}",
     "27":"{4fe21c76-1760-437b-a2f2-99909130a175}",
     "30":"{6953bc3b-6768-4291-8410-7914ce6e2ca8}",
+    "31":"{4afcba0b-13e4-47c3-bebe-477428b46913}",
     } [major+minor]
 
 # Compute the name that Sphinx gives to the docfile