Add v6.4.2 to CHANGELOG.md [skip ci]

Author: Austin Green

CHANGELOG.md

@@ -12,6 +12,17 @@ _Note: Gaps between patch versions are faulty, broken or test releases._
 <!-- DO NOT MODIFY BELOW THIS COMMENT -->
 <!-- insert-new-changelog-here -->
 
+## v6.4.2 (2019-08-16)
+
+#### :bug: Bug Fix
+* `dropdowns`
+  * [#414](https://github.com/zendeskgarden/react-components/pull/414) fix(dropdowns): persist cursor location in Autocomplete ([@austin94](https://github.com/austin94))
+
+#### :seedling: Internal
+* [#407](https://github.com/zendeskgarden/react-components/pull/407) chore(deps): update dependency commander to v3 ([@renovate[bot]](https://github.com/apps/renovate))
+* [#405](https://github.com/zendeskgarden/react-components/pull/405) chore(deps): update all development non-major dependencies ([@renovate[bot]](https://github.com/apps/renovate))
+* [#406](https://github.com/zendeskgarden/react-components/pull/406) chore(deps): update dependency @testing-library/react to v9 ([@renovate[bot]](https://github.com/apps/renovate))
+
 ## v6.4.1 (2019-08-12)
 
 #### :bug: Bug Fix