test: fix bar tests
test: fix bar tests

* Fixed the bar tests that make use of the attribute offset. The values
  of the bar center in these tests were incorrect.

iongroup/plotly.js,aburato/plotly.js,iongroup/plotly.js,plotly/plotly.js,plotly/plotly.js,iongroup/plotly.js,asolagmbh/plotly.js,asolagmbh/plotly.js,aburato/plotly.js,etpinard/plotly.js,asolagmbh/plotly.js,plotly/plotly.js,etpinard/plotly.js,etpinard/plotly.js,plotly/plotly.js