Add v6.4.3 to CHANGELOG.md [skip ci]

Author: Austin Green

CHANGELOG.md

@@ -12,6 +12,18 @@ _Note: Gaps between patch versions are faulty, broken or test releases._
 <!-- DO NOT MODIFY BELOW THIS COMMENT -->
 <!-- insert-new-changelog-here -->
 
+## v6.4.3 (2019-08-23)
+
+#### :bug: Bug Fix
+* `datepickers`
+  * [#415](https://github.com/zendeskgarden/react-components/pull/415) fix(datepicker): correct minValue and maxValue displays and allow same date selection within Range ([@austin94](https://github.com/austin94))
+
+#### :memo: Documentation
+* `theming`
+  * [#421](https://github.com/zendeskgarden/react-components/pull/421) docs: correct react-theming peer dependencies ([@vhiairrassary](https://github.com/vhiairrassary))
+* `forms`
+  * [#422](https://github.com/zendeskgarden/react-components/pull/422) docs(forms): Checkbox example in forms is throwing ([@ryanseddon](https://github.com/ryanseddon))
+
 ## v6.4.2 (2019-08-16)
 
 #### :bug: Bug Fix