Update CHANGELOG.rst

Author: hynek

CHANGELOG.rst

@@ -130,7 +130,7 @@ Backward-incompatible Changes
 
 - ``attr.define()``, ``attr.frozen()``, ``attr.mutable()``, and ``attr.field()`` remain **provisional**.
 
-  This release does **not** change change anything about them and they are already used widely in production though.
+  This release does **not** change anything about them and they are already used widely in production though.
 
   If you wish to use them together with mypy, you can simply drop `this plugin <https://gist.github.com/hynek/1e3844d0c99e479e716169034b5fa963#file-attrs_ng_plugin-py>`_ into your project.