Storyboard: Support invalid tasks in update script

These exist.  They should not be on the board.

Change-Id: Idf496ab70887280adff8a627c0d14a10688e7c5b
diff --git a/tools/update-storyboard.py b/tools/update-storyboard.py
index 6800a35..12e6916 100644
--- a/tools/update-storyboard.py
+++ b/tools/update-storyboard.py
@@ -67,6 +67,7 @@
     'inprogress': ['In Progress', 'Blocked'],
     'review': ['In Progress', 'Blocked'],
     'merged': None,
+    'invalid': None,
 }