use semver-valid development version scheme

Kriechi · pgjones · commit ed7d684c0ab7 · 2020-08-02T17:08:36.000+01:00
diff --git a/HISTORY.rst b/HISTORY.rst
@@ -1,7 +1,7 @@
 Release History
 ===============
 
-6.0.0dev0
+6.0.0+dev
 ---------
 
 **API Changes (Backward-compatible)**
diff --git a/hyperframe/__init__.py b/hyperframe/__init__.py
@@ -5,4 +5,4 @@
 
 A module for providing a pure-Python HTTP/2 framing layer.
 """
-__version__ = '5.2.0'
+__version__ = '6.0.0+dev'
