solve::TAOSolver: add [[nodiscard]]

solve/src/include/ae108/solve/TAOSolver.h

@@ -89,7 +89,7 @@ public:
    * @param assembleStiffnessMatrix A valid callable. It will be called to
    * assemble the stiffness matrix.
    */
-  cpppetsc::distributed<vector_type>
+  [[nodiscard]] cpppetsc::distributed<vector_type>
   computeSolution(const BoundaryConditionContainer &boundaryConditions,
                   cpppetsc::distributed<vector_type> initialGuess,
                   const double time, LocalEnergyAssembler assembleEnergy,
@@ -122,7 +122,7 @@ public:
    * @param assembleStiffnessMatrix A valid callable. It will be called to
    * assemble the stiffness matrix.
    */
-  cpppetsc::distributed<vector_type> computeSolution(
+  [[nodiscard]] cpppetsc::distributed<vector_type> computeSolution(
       const BoundaryConditionContainer &boundaryConditions,
       cpppetsc::distributed<vector_type> initialGuess, const double time,
       DistributedEnergyAssembler assembleEnergy,