use PEP440 version string
@@ -45,7 +45,7 @@ A tiny example:
__docformat__ = "restructuredtext en"
# The format of the __version__ line is matched by a regex in setup.py
-__version__ = "6.0.0-pre-alpha"
+__version__ = "6.0.0-alpha"
__date__ = "2021-03-22"
__all__ = [
