bump version to 0.2.1 (#129)

Author: scottstanie

src/s1reader/version.py

@@ -4,6 +4,7 @@
 # release history
 Tag = collections.namedtuple('Tag', 'version date')
 release_history = (
+    Tag('0.2.1', '2023-08-23'),
     Tag('0.2.0', '2023-07-25'),
     Tag('0.1.7', '2023-05-09'),
     Tag('0.1.6', '2023-03-22'),