fix: add missing return

Author: rschwarz

mip/highs.py

@@ -785,7 +785,7 @@ def var_set_column(self: "SolverHighs", var: "mip.Var", value: "Column"):
     def var_get_rc(self: "SolverHighs", var: "mip.Var") -> numbers.Real:
         # TODO: double-check this!
         if self._rc:
-            self._rc[var.idx]
+            return self._rc[var.idx]
 
     def var_get_x(self: "SolverHighs", var: "mip.Var") -> numbers.Real:
         if self._x: