Add Conduit to adopters (#2981)

ADOPTERS.md

@@ -9,6 +9,9 @@ production users that have added themselves (in alphabetical order):
   API of [Chef Automate](https://automate.chef.io/). Furthermore, the generated
   OpenAPI data serves as the basis for its [API documentation](https://automate.chef.io/docs/api/).
   The code is Open Source, [see `github.com/chef/automate`](https://github.com/chef/automate).
+- [Conduit](https://github.com/ConduitIO/conduit), a data streaming tool written in Go,
+  uses the gRPC-Gateway since its very beginning to provide an HTTP API in addition to its gRPC API. 
+  This makes it easier to integrate with Conduit, and the generated OpenAPI data is used in the documentation.
 - [Scaleway](https://www.scaleway.com/en/) uses the gRPC-Gateway since 2018 to
   serve millions of API requests per day [1].
 - [SpiceDB](https://github.com/authzed/spicedb) uses the gRPC-Gateway to handle