SCIP returns LpStatusUnbounded when the problem is unbounded (#801)

* SCIP returns LpStatusUnbounded when the problem is unbounded

* add SCIP_PY to github actions

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Co-authored-by: Franco Peschiera <pchtsp@gmail.com>

.github/workflows/pythonpackage.yml

@@ -67,5 +67,8 @@ jobs:
       - name: Install swat
         run: |
           python -m pip install swat
+      - name: Install SCIP_PY
+        run: |
+          python -m pip install pyscipopt
       - name: Test with pulptest
         run: pulptest

pulp/tests/test_pulp.py

@@ -835,7 +835,7 @@ def test_elastic_constraints_penalty_unbounded(self):
             elif self.solver.__class__ is GLPK_CMD:
                 # GLPK_CMD Does not report unbounded problems, correctly
                 pulpTestCheck(prob, self.solver, [const.LpStatusUndefined])
-            elif self.solver.__class__ in [GUROBI_CMD, SCIP_CMD, FSCIP_CMD, SCIP_PY]:
+            elif self.solver.__class__ in [GUROBI_CMD, FSCIP_CMD]:
                 pulpTestCheck(prob, self.solver, [const.LpStatusNotSolved])
             elif self.solver.__class__ in [CHOCO_CMD]:
                 # choco bounds all variables. Would not return unbounded status