Fix CI

Signed-off-by: Francisco Martín Rico <fmrico@gmail.com>

Author: fmrico

.github/workflows/humble.yaml

@@ -16,6 +16,8 @@ jobs:
         os: [ubuntu-22.04]
       fail-fast: false
     steps:
+      - name: Repo checkout
+        uses: actions/checkout@v2
       - name: Setup ROS 2
         uses: ros-tooling/setup-ros@0.7.1
         with: