Update CHANGELOG.md

Co-authored-by: Sabrina Krakau <sabrinakrakau@gmail.com>

Author: WackerO

CHANGELOG.md

@@ -7,7 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
-- [#250](https://github.com/qbic-pipelines/rnadeseq/pull/250) Added clearer error for incorrect contrast_pairs
+- [#250](https://github.com/qbic-pipelines/rnadeseq/pull/250) Added clearer error message for incorrect contrast_pairs
 
 ### Fixed