.bumpversion: Update current_version

.bumpversion.cfg

@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 4.0.0rc2
+current_version = 4.0.0
 commit = True
 tag = True
 parse = (?P<major>\d+)\.(?P<minor>\d+)\.(?P<patch>\d+)(?P<releaselevel>[a-z]+)?