change version to hopefully a valid beta name

Author: NSoiffer

buildVars.py

@@ -34,7 +34,7 @@ def _(arg):
         Other language and braille code translations are in progress.""",
     ),
     # version
-    "addon_version": "0.7.6beta9",
+    "addon_version": "0.7.6b9",
     # Author(s)
     "addon_author": "Neil Soiffer <soiffer@alum.mit.edu>",
     # URL for the add-on documentation support