bump version to 4.9.1dev

Author: boegel

easybuild/tools/version.py

@@ -45,7 +45,7 @@
 # recent setuptools versions will *TRANSFORM* something like 'X.Y.Zdev' into 'X.Y.Z.dev0', with a warning like
 #   UserWarning: Normalizing '2.4.0dev' to '2.4.0.dev0'
 # This causes problems further up the dependency chain...
-VERSION = LooseVersion('4.9.0')
+VERSION = LooseVersion('4.9.1.dev0')
 UNKNOWN = 'UNKNOWN'