Typo in gz sim python api

[CreeperLin]

The Python bindings define Joint.set_position_imits where it should be set_position_limits

gz-sim/python/src/gz/sim/Joint.cc

Line 97 in f600a44

.def("set_position_imits", &gz::sim::Joint::SetPositionLimits,

[ahcorde]

Fixed PR #2578