docs: update CHANGELOG

Author: RHReynolds

CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Enhancements and fixes
 
 - [[PR #1121](https://github.com/nf-core/rnaseq/pull/1121) - Changes for 3.13.1 patch release incl. igenomes star fix
+- [[PR #1126](https://github.com/nf-core/rnaseq/pull/1126) - Fixes error when transcript_fasta not provided and skip_gtf_filter set to true (issue [#1125](https://github.com/nf-core/rnaseq/issues/1125))
 
 ## [[3.13.0](https://github.com/nf-core/rnaseq/releases/tag/3.13.0)] - 2023-11-17