CHANGELOG.md in sendgrid-ruby-6.3.9 vs CHANGELOG.md in sendgrid-ruby-6.4.0

@@ -1,7 +1,13 @@
 # Change Log
 All notable changes to this project will be documented in this file.
 
+[2021-02-10] Version 6.4.0
+--------------------------
+**Library - Feature**
+- [PR #455](https://github.com/sendgrid/sendgrid-ruby/pull/455): Add http_options as a param in the SendGrid::API's constructor. Thanks to [@hoangtuanictvn](https://github.com/hoangtuanictvn)!
+
+
 [2021-01-27] Version 6.3.9
 --------------------------
 **Library - Fix**
 - [PR #446](https://github.com/sendgrid/sendgrid-ruby/pull/446): Accurate duplicate checking when adding email to Personalizations. Thanks to [@mito5525](https://github.com/mito5525)!
 - [PR #457](https://github.com/sendgrid/sendgrid-ruby/pull/457): email is required. Thanks to [@luk4s](https://github.com/luk4s)!