[accelerator] set accel graph bar min height

frontend/src/app/components/acceleration/acceleration-fees-graph/acceleration-fees-graph.component.ts

@@ -247,6 +247,7 @@ export class AccelerationFeesGraphComponent implements OnInit, OnDestroy {
           type: 'bar',
           barWidth: '90%',
           large: true,
+          barMinHeight: 1,
         },
       ],
       dataZoom: (this.widget || data.length === 0 )? undefined : [{