add changes to CHANGELOG.md

Author: StijnCaerts

CHANGELOG.md

@@ -20,6 +20,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 - Corrected the closing of client connections in ES index management functions [#132](https://github.com/stac-utils/stac-fastapi-elasticsearch/issues/132)
 - Corrected the automatic converstion of float values to int when building Filter Clauses [#135](https://github.com/stac-utils/stac-fastapi-elasticsearch/issues/135)
+- Remove unsupported characters from Elasticsearch index names [#153](https://github.com/stac-utils/stac-fastapi-elasticsearch/issues/153)
 
 ## [v0.3.0]