Add octomachinery to third-party projects

Author: webknjaz

docs/third_party.rst

@@ -109,6 +109,9 @@ They may be perfect or not -- we don't know.
 Please add your library reference here first and after some time
 period ask to raise the status.
 
+- `octomachinery <https://octomachinery.dev>`_ A framework for developing
+  GitHub Apps and GitHub Actions. Python 3.7+ is required.
+
 - `aiomixcloud <https://github.com/amikrop/aiomixcloud>`_
   Mixcloud API wrapper for Python and Async IO.