fix date

Author: ksvirkou-hubspot

CHANGELOG.md

@@ -7,7 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased](https://github.com/HubSpot/hubspot-api-php/compare/2.6.0...HEAD)
 
-## [2.6.0](https://github.com/HubSpot/hubspot-api-php/releases/tag/2.6.0) - 2021-01-18
+## [2.6.0](https://github.com/HubSpot/hubspot-api-php/releases/tag/2.6.0) - 2021-01-19
 
 ### Added