Fix changelog

Author: weiznich

CHANGELOG.md

@@ -52,3 +52,5 @@ for Rust libraries in [RFC #1105](https://github.com/rust-lang/rfcs/blob/master/
 [0.2.1]: https://github.com/weiznich/diesel_async/compare/v0.2.0...v0.2.1
 [0.2.2]: https://github.com/weiznich/diesel_async/compare/v0.2.1...v0.2.2
 [0.3.0]: https://github.com/weiznich/diesel_async/compare/v0.2.0...v0.3.0
+[0.3.1]: https://github.com/weiznich/diesel_async/compare/v0.3.0...v0.3.1
+[0.3.2]: https://github.com/weiznich/diesel_async/compare/v0.3.1...v0.3.2