Updated CHANGELOG

Signed-off-by: Raúl Naveiras <me@raulnaveiras.com>

Author: rnaveiras

CHANGELOG.md

@@ -20,6 +20,8 @@ We use *breaking* word for marking changes that are not backward compatible (rel
 
 ### Changed
 
+- [#2194](https://github.com/thanos-io/thanos/pull/2194) Updated to golang v1.14.2
+
 ## [v0.12.0](https://github.com/thanos-io/thanos/releases/tag/v0.12.0) - 2020.04.15
 
 ### Fixed