Bar Chart Value Labels missing

## What did you do?

Create a Bar Chart view. Create a data set where all values are negative.

## What did you expect to happen?

Expect the value labels to be rendered.

## What happened instead?

Value labels do not always render. They may show up or disappear depending on the size of the chart view or containing view/window.
Easy to see when running in a Mac app and dragging the window size bigger or smaller.

Only seems to happen when all values are negative. With positive bar charts seems to be fine.

## DGCharts Environment

**DGCharts version/Branch/Commit Number: Current and any previous**
**Xcode version: 15.x and 14.x**
**Platform(s) running DGCharts: iOS 15+ and macOS 12+**

Reproduce the issue in a DGCharts Bar Chart using a data set with only negative values on iOS or macOS. Resize the chart or containing window while observing the value labels; done means the labels render consistently regardless of chart size.

Written by the indexing model from the issue text.