Describe the bug
There appears to be a minor issue with the borders if the border size is set to zero.

To Reproduce
Steps to reproduce the behavior:

1. Using the sample, go to 'Settings'
2. Set the 'Border Thickness' to zero (Click on the '-" button until it darkens).
3. Close the settings and observe the vertical border between different columns. Resizing the window may be necessary to see the issue.
4. Resizing the window causes the vertical border issue to appear, disappear, or move. There may be zero, one, or more than one vertical border.

Expected behavior
When the border size is set to zero, no vertical borders should be visible.

Screenshots
First example:

After changing the size of the window, the bar has moved:

Desktop (please complete the following information):

• OS: Windows
• Version 10.0.19044
• Maui.DataGrid version 4.0.3