chore: update changelog

Signed-off-by: Charlike Mike Reagent <[email protected]>

Author: tunnckoCore

CHANGELOG.md

@@ -14,6 +14,7 @@
  * feat: use Modern Streams API ([#531](https://github.com/node-formidable/node-formidable/pull/531))
  * fix: remove gently hijack and tests (([#539](https://github.com/node-formidable/node-formidable/pull/539)))
  * docs: Clarify supported hash algorithms (([#537](https://github.com/node-formidable/node-formidable/pull/537)))
+ * feat: better tests, add Airbnb + Prettier(([#542](https://github.com/node-formidable/node-formidable/pull/542)))
 
 ### v1.2.1 (2018-03-20)