Release version 0.5.1

.bumpversion.cfg

 [bumpversion]
-current_version = 0.5.1.dev
+current_version = 0.5.1
 parse = (?P<major>\d+)\.(?P<minor>\d+)\.(?P<patch>\d+)(\.(?P<release>[a-z0-9]+))?
 serialize = 
 	{major}.{minor}.{patch}.{release}

setup.cfg

 [metadata]
 name = workflow-utils
-version = 0.5.1.dev
+version = 0.5.1
 author = Andrew Otto
 author_email = otto@wikimedia.org
 description = Common libraries for data engineering workflows at WMF.