[PHYSICS] Contact geometry pair checks are now strictly limited to tuples

[ShravanTata]

In Physics module, currently contacts are initialized by checking contact pairs. The pairs now have to be strictly tuples. This is a limitation as we could also use python lists (which are standard types in YAML).

farms_mujoco/farms_mujoco/simulation/physics.py

Line 359 in 8f02900

# Contacts