element form如何在 label 前面添加必填 红星

<el-form-item label="缺陷子类型" :required="true" style="text-align:left">
                <el-select
                  clearable
                  placeholder="请选择"
                  dir="rtl"
                  v-model="flowData.frmData.defectItemName"
                  @change="choosechildDefect"
                  style="width:200px"
                >
                  <el-option
                    v-for="item in childDefectData"
                    :key="item.id"
                    :label="item.childDefectName"
                    :value="item.childDefectName"
                  ></el-option>
                </el-select>
</el-form-item>