add (failing) test case for simple histogram

width: 1200px;

height: 480px;

plot {

  data: csv(tests/testdata/histogram.csv);

  y: var1;

  x: var0;

  axis-top: off;

  axis-y: log;

  axis-x: categorical;

  axis-y-max: 80000;

  grid-x: geom;

  layer {

    type: bars;

    labels: var1;

  }

  legend {

    position: top left inside;

  }

}

var0,var1

1,4945

2,45

3,6

4,4

5,2

6,1