[12.0][IMP][web_widget_bokeh_chart] Render readonly the widget to permit dynamic updates

web_widget_bokeh_chart/static/src/js/web_widget_bokeh_chart.js

@@ -5,7 +5,7 @@ odoo.define('web_widget_bokeh_chart', function (require) {
     var AbstractField = require('web.AbstractField');
 
     var BokehChartWidget = AbstractField.extend({
-        start: function() {
+        _renderReadonly: function() {
             var val = this.value;
             this.$el.html(val);
         }