Add a changelog entry for attrs support (#1371)

Author: jacobbogdanov

ChangeLog

@@ -15,6 +15,11 @@ Release date: TBA
 
   Closes PyCQA/pylint#5679
 
+* Add support for [attrs v21.3.0](https://github.com/python-attrs/attrs/releases/tag/21.3.0) which
+  added a new `attrs` module alongside the existing `attr`.
+
+  Closes #1330
+
 What's New in astroid 2.9.4?
 ============================
 Release date: TBA