Update CHANGELOG

Author: jgranick

CHANGELOG.md

@@ -1,3 +1,17 @@
+3.1.0 (08/31/2022)
+------------------
+
+* Added support for OpenFL 9.2 `@:bind` to extend SWF symbol classes
+* Added support to extend `Sprite` classes (in addition to `MovieClip`)
+* Added initial support for SWC files
+* Added support for multiple labels per frame in Animate libraries
+* Improved `MovieClip` animation performance in Animate libraries
+* Improved class generation to allow `generate="false"` to disable
+* Fixed initialization order to allow extending generating classes
+* Fixed support for `Assets.exists` without specifying asset type
+* Fixed `Std.is` deprecation warnings
+
+
 3.0.2 (09/16/2020)
 ------------------