[Tests] Warnings that should be resolved

[mmcky]

• game_theory/normal_form_game.py:485

.............................................................................../QuantEcon.py/quantecon/game_theory/normal_form_game.py:485: OptimizeWarning: Solving system with option 'cholesky':True failed. It is normal for this to happen occasionally, especially as the solution is approached. However, if you see this frequently, consider setting option 'cholesky' to False.
  res = linprog(c, A_ub=A, b_ub=b, method=method)
/QuantEcon.py/quantecon/game_theory/normal_form_game.py:485: OptimizeWarning: Solving system with option 'sym_pos':True failed. It is normal for this to happen occasionally, especially as the solution is approached. However, if you see this frequently, consider setting option 'sym_pos' to False.
  res = linprog(c, A_ub=A, b_ub=b, method=method)
//anaconda3/envs/pip-latest/lib/python3.7/site-packages/scipy/optimize/_linprog_ip.py:110: LinAlgWarning: Ill-conditioned matrix (rcond=4.28312e-17): result may not be accurate.
  return sp.linalg.solve(M, r, sym_pos=sym_pos)