Correct Ppython fallback branch (#5884)

Signed-off-by: Mario Dominguez <[email protected]>

Author: Mario-DL

.github/workflows/reusable-ubuntu-ci.yml

@@ -313,7 +313,7 @@ jobs:
         uses: eProsima/eProsima-CI/ubuntu/get_related_branch_from_repo@v0
         with:
           remote_repository: eProsima/Fast-DDS-python
-          fallback_branch: main
+          fallback_branch: 2.2.x
 
       - name: Download Fast DDS Python repo
         uses: eProsima/eProsima-CI/external/checkout@v0