correct path in test_dumux.sh

scripts/test_dumux.sh

 # Compile and runs a simple
 # one-phase ground water flow example
 # and visualizes the result using paraview.
-cd dumux/build-cmake/test/porousmediumflow/1p/implicit/incompressible
+cd dumux/build-cmake/test/porousmediumflow/1p/incompressible
 echo "Compiling a one-phase test using a cell-centered TPFA discretization (might take a while)..."
 make -B test_1p_incompressible_tpfa_anadiff
 echo "Running simulation..."