[career] Correct if collections in solve_model

[kuramogura]

The behavior of the current code

cw = CareerWorkerProblem()
v_star = solve_model(cw,verbose=True,max_iter = 500)

Error at iteration 25 is 1.4599451216938633.
Error at iteration 50 is 0.40497355408797375.
Error at iteration 75 is 0.11233544129407846.
Error at iteration 100 is 0.03116068010700701.
Error at iteration 125 is 0.008643647753075356.
Error at iteration 150 is 0.0023976577604400973.
Error at iteration 175 is 0.0006650852626535197.
Error at iteration 200 is 0.00018448771709245193.

Converged in 212 iterations.

v_star = solve_model(cw,verbose=True,max_iter = 212)

Error at iteration 25 is 1.4599451216938633.
Error at iteration 50 is 0.40497355408797375.
Error at iteration 75 is 0.11233544129407846.
Error at iteration 100 is 0.03116068010700701.
Error at iteration 125 is 0.008643647753075356.
Error at iteration 150 is 0.0023976577604400973.
Error at iteration 175 is 0.0006650852626535197.
Error at iteration 200 is 0.00018448771709245193.
Failed to converge!

This pull request corrects if conditions in solve_model.

[jstac]

Thanks @kuramogura . This is helpful.