correct test

Author: gabrielaznar

climada/engine/test/test_cost_benefit.py

@@ -373,7 +373,7 @@ def test_calc_no_change_pass(self):
 class TestRiskFuncs(unittest.TestCase):
     '''Test risk functions definitions'''
 
-    def test_impact():
+    def test_impact(self):
         ent = Entity()
         ent.read_excel(ENT_DEMO_TODAY)
         ent.check()