release: update release notes for 0.3.1
I forgot to do this when I bumped the version number.
@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
## [Unreleased]
+## [0.3.1] - 2022-03-13
+
### Fixed bugs
- (#131) Fixed crash when `core.excludesFile` pointed to non-existent file, and
