Steps to reproduce

1. Create a plot with CategoryAxis as X and LinearAxis as Y. Specify the MajorStep for the CategoryAxis
2. Check ticks on the CategoryAxis

Platform: Windows
.NET version: 6

Expected behaviour

As I have 24 items and step = 4, I don't expect the "empty" tick in the end

Actual behaviour

There is an extra tick

You can find plot model here (it has a lot of additional settings, but the bug is reproducible without them):
https://github.com/goremykin/oxyplot-example/blob/main/WinFormsApp1/Form1.cs

Also you can just clone and run this app:
https://github.com/goremykin/oxyplot-example

Minor: additionally I would like to draw your attention to the margin at the left side of the plot. There is no margin at the right side and at the bottom, but there is small margin at the left side.