[IPC 2023] Issues grounding `labyrinth` benchmark

[miquelramirez]

@anubhav-cs reports an issue on the IPC-23 labyrinth benchmark:

Traceback (most recent call last):
  File "/builds/Release/lapkt_package/lapkt.py", line 41, in <module>
    planner = Planner(config)
  File "/builds/Release/lapkt_package/lapkt/load_planner.py", line 85, in __init__
    self._load_problem()
  File "/builds/Release/lapkt_package/lapkt/load_planner.py", line 140, in _load_problem
    process_task(
  File "/builds/Release/lapkt_package/lapkt/pddl/tarski/tarski_util.py", line 194, in ground_generate_task
    reachable_action_params =   copy.deepcopy( grounding.ground_actions())
  File "/usr/local/lib/python3.10/dist-packages/tarski_lapkt/grounding/lp_grounding.py", line 52, in ground_actions
    model = self._solve_lp()
  File "/usr/local/lib/python3.10/dist-packages/tarski_lapkt/grounding/lp_grounding.py", line 76, in _solve_lp
    raise ReachabilityLPUnsolvable()
tarski_lapkt.grounding.errors.ReachabilityLPUnsolvable: The relaxed-reachabilty logic program is not solvable

labyrinth-issue-instance.zip