[test][dambreak] Add zero threshold for y-velocity

test/freeflow/shallowwater/dambreak/CMakeLists.txt

@@ -6,5 +6,6 @@ dune_add_test(NAME test_shallowwater_dambreak
               CMD_ARGS       --script fuzzy
                              --files ${CMAKE_SOURCE_DIR}/test/references/test_ff_shallowwater_dambreak-reference.vtu
                                      ${CMAKE_CURRENT_BINARY_DIR}/dambreak-00001.vtu
+                             --zeroThreshold {"velocityY":1e-14}
                              --command "${CMAKE_CURRENT_BINARY_DIR}/test_shallowwater_dambreak params.input
                              -Problem.Name dambreak")