Add hatsu to ECOSYSTEM.md (#2462)

ECOSYSTEM.md

@@ -81,6 +81,7 @@ If your project isn't listed here and you would like it to be, please feel free
 - [ReductStore](https://github.com/reductstore/reductstore): A time series database for storing and managing large amounts of blob data
 - [randoku](https://github.com/stchris/randoku): A tiny web service which generates random numbers and shuffles lists randomly
 - [sero](https://github.com/clowzed/sero): Host static sites with custom subdomains as surge.sh does. But with full control and cool new features. (axum, sea-orm, postgresql)
+- [Hatsu](https://github.com/importantimport/hatsu): 🩵 Self-hosted & Fully-automated ActivityPub Bridge for Static Sites.
 
 [Realworld]: https://github.com/gothinkster/realworld
 [SQLx]: https://github.com/launchbadge/sqlx