Update release date for 1.1.0

Author: m-mohr

CHANGELOG.md

@@ -6,7 +6,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased / Draft
 
-## [1.1.0] - 2021-06-15
+## [1.1.0] - 2021-05-17
 
 ### Added
 - `GET /processes` and `GET` / `PUT` for `/process_graphs/{process_graph_id}`: Allow specifying the return values processes receive from child processes. [#350](https://github.com/Open-EO/openeo-api/issues/350)