bump tolerence in Drawing.bbox test
bump tolerence in Drawing.bbox test

... to pass ok on etpinard's laptop running Chrome 70

plotly/plotly.js,etpinard/plotly.js,etpinard/plotly.js,aburato/plotly.js,aburato/plotly.js,etpinard/plotly.js,plotly/plotly.js,plotly/plotly.js,plotly/plotly.js