Updadte changelog to include fix for #1593

Author: timothycrosley

CHANGELOG.md

@@ -6,6 +6,7 @@ Find out more about isort's release policy [here](https://pycqa.github.io/isort/
 
 ### 5.7.0 December TBD
   - Fixed #1612: In rare circumstances an extra comma is added after import and before comment.
+  - Fixed #1593: isort encounters bug in Python 3.6.0.
   - Implemented #1596: Provide ways for extension formatting and file paths to be specified when using streaming input from CLI.
   - Implemented #1583: Ability to output and diff within a single API call to `isort.file`.
   - Implemented #1562, #1592 & #1593: Better more useful fatal error messages.