[Cleanup] Use auto ->

src/solverfactory.cc

@@ -52,8 +52,8 @@ SolverFactory<dim, BlockProblemType, GridType>::~SolverFactory() {
 }
 
 template <size_t dim, class BlockProblemType, class GridType>
-typename SolverFactory<dim, BlockProblemType, GridType>::SolverType *
-SolverFactory<dim, BlockProblemType, GridType>::getSolver() {
+auto SolverFactory<dim, BlockProblemType, GridType>::getSolver()
+    -> SolverType *{
   return multigridStep;
 }