Fix humble binary build (ros-controls#213) (ros-controls#214)

(cherry picked from commit 02d78ec)

Co-authored-by: Christoph Fröhlich <[email protected]>

Author: mergify[bot]

.github/workflows/humble-binary-downstream-build.yml

@@ -18,7 +18,7 @@ jobs:
     with:
       ros_distro: humble
       ros_repo: testing
-      ref_for_scheduled_build: master
+      ref_for_scheduled_build: humble
       not_test_build: true
       downstream_workspace: ros_controls.humble.repos
       not_test_downstream: true