If you want to have more prereleases than default so you have to enable deploy on all branches. ref.: https://docs.travis-ci.com/user/deployment#examples-of-conditional-deployment
semantic-release documentation
- Usage - semantic-release installation and configuration
- Extending- Extending semantic-release with plugins and shareable configurations
- Recipes - Community written recipes for common semantic-release use-cases
- Developer Guide - The essentials of writing a semantic-release plugin or shareable configurations
- Support - FAQ and troubleshooting