dev: Bump version to 6.0.1+git

Author: tsibley

CHANGES.md

@@ -7,7 +7,11 @@ This changelog is intended for _humans_ and follows many of the principles from
 Versions for this project follow the [Semantic Versioning
 rules](https://semver.org/spec/v2.0.0.html).  Each heading below is a version
 released to [PyPI](https://pypi.org/project/nextstrain-cli/) and the date it
-was released.
+was released.  The "__NEXT__" heading below describes changes in the unreleased
+development source code and as such may not be routinely kept up to date.
+
+
+# __NEXT__
 
 
 # 6.0.1 (3 January 2023)

nextstrain/cli/__version__.py

@@ -1 +1 @@
-__version__ = '6.0.1'
+__version__ = '6.0.1+git'