Handle non-convergence in Simplex method

Raise ValueError if Simplex does not converge within max iterations.

Author: aryanexe07

linear_programming/simplex.py

@@ -302,7 +302,10 @@ def run_simplex(self) -> dict[Any, Any]:
                 self.tableau = self.change_stage()
             else:
                 self.tableau = self.pivot(row_idx, col_idx)
-        return {}
+        raise ValueError(
+            f"Simplex did not converge within {Tableau.maxiter} iterations. "
+            "The problem may be cycling or unbounded."
+        )
 
     def interpret_tableau(self) -> dict[str, float]:
         """Given the final tableau, add the corresponding values of the basic