ci: backport: Update backport action to v1.1.1-3

This commit updates the backport workflow to use the backport action
v1.1.1-3, which introduces the following enhancements:

1. Cherry-pick backport commits with the `-x` option to improve
   traceability.

2. Disable incorrect warning when "rebase merge" method is enabled.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>