ci: retrigger after transient pr-merge infra failure

The pr-merge run on Jenkins PR-10522 failed for infrastructure reasons
unrelated to the patch:

  - All 8035 tests passed (100% tests passed, 0 tests failed).
  - After the test stage, Jenkins hit "ERROR: Timeout after 180 seconds"
    waiting for a worker pod, then "Caught exception: Failed to rm
    container ..." / "Detected transient container removal error."

Pushing an empty commit on top of the master merge to retrigger CI
without rewriting history.

Signed-off-by: Øyvind Harboe <oyvind.harboe@zylin.com>

Author: oharboe