Remove useless yAxisTitle setter

sample/src/main/java/com/github/aachartmodel/aainfographics/demo/chartcomposer/ChartOptionsComposer.kt

@@ -1125,7 +1125,6 @@ function () {
             .chartType(AAChartType.Areaspline) //图表类型
             .colorsTheme(arrayOf("#04d69f", "#1e90ff", "#ef476f", "#ffd066"))
             .stacking(AAChartStackingType.Normal)
-            .yAxisTitle("") //设置 Y 轴标题
             .yAxisVisible(false)
             .markerRadius(0f)
             .series(arrayOf(element1, element2, element3, element4))

sample/src/main/java/com/github/aachartmodel/aainfographics/demo/chartcomposer/CustomStyleChartComposer.kt

@@ -335,7 +335,6 @@ object CustomStyleChartComposer  {
         return AAChartModel()
             .chartType(AAChartType.Spline)
             .backgroundColor("#4b2b7f")
-            .yAxisTitle("")//设置Y轴标题
             .dataLabelsEnabled(false)//是否显示值
             .tooltipEnabled(true)
             .markerRadius(0f)
@@ -356,7 +355,6 @@ object CustomStyleChartComposer  {
 
         return AAChartModel()
             .chartType(AAChartType.Column)
-            .yAxisTitle("")//设置Y轴标题
             .dataLabelsEnabled(false)//是否显示值
             .tooltipEnabled(false)
             .markerRadius(0f)
@@ -380,7 +378,6 @@ object CustomStyleChartComposer  {
 
         return AAChartModel()
             .chartType(AAChartType.Area)
-            .yAxisTitle("")//设置Y轴标题
             .yAxisGridLineWidth(0f)
             .categories(arrayOf("Jan", "Feb", "Mar", "Apr", "May", "Jun", "July", "Aug", "Spe", "Oct", "Nov", "Dec"))
             .dataLabelsEnabled(false)//是否显示值

sample/src/main/java/com/github/aachartmodel/aainfographics/demo/chartcomposer/CustomTooltipComposer.kt

@@ -661,7 +661,6 @@ function () {
     fun customTooltipWhichDataSourceComeFromOutSideRatherThanSeries(): AAOptions {
         val aaChartModel = AAChartModel()
             .chartType(AAChartType.Column) //图表类型
-            .yAxisTitle("") //设置 Y 轴标题
             .yAxisLineWidth(1f) //Y轴轴线线宽为0即是隐藏Y轴轴线
             .yAxisGridLineWidth(1f) //y轴横向分割线宽度为1(为0即是隐藏分割线)
             .xAxisGridLineWidth(1f) //x轴横向分割线宽度为1(为0即是隐藏分割线)