fixes CG wrongly stabilizing farkas pricing #87

Job	Run time
Tests with modeling interface	3m 30s
Tests with Mosek (branch-and-bound/test_bab_knapsack_Mosek)	9m 1s
Tests with GLPK (branch-and-bound/test_bab_knapsack_GLPK)	5m 16s
Tests with HiGHS (branch-and-bound/test_bab_knapsack_HiGHS)	9m 18s
Tests with Mosek (branch-and-bound/test_bab_location_Mosek)	6m 50s
Tests with GLPK (branch-and-bound/test_bab_location_GLPK)	5m 39s
Tests with HiGHS (branch-and-bound/test_bab_location_HiGHS)	10m 33s
Tests with Mosek (branch-and-price/test_bap_assignment_Mosek)	10m 6s
Tests with GLPK (branch-and-price/test_bap_assignment_GLPK)	4m 17s
Tests with HiGHS (branch-and-price/test_bap_assignment_HiGHS)	10m 29s
Upload coverage report	14s
	1h 15m 13s

Provide feedback