Update CHANGELOG

Author: stouset

sudo_plugin/CHANGELOG.md

@@ -32,6 +32,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
   crossing FFI boundaries. All panics are caught at the boundaries and
   turned into an appropriate error type.
 
+- No longer segfaults against sudo >= 1.9 which introduced API changes that
+  require the ability to write into the plugin.
+
 ## [1.2.0] - 2020-03-26
 
 ### Added