MacOS: errors when validating the layout with the dtd file

[gagbo]

As discussed on discord, xmllint is harder to run on the generated .keylayout because its parser chokes.

So this is a screen capture of VSCodium using the RedHat XML extension. Note that:

• all errors are visible in the error list at the bottom,
• the buffer part of the screenshot shows lines that work and lines that trigger errors,
• the errors only appear once I fix the path to the dtd file (see #167 ), so I highly suspect they are indeed coming from dtd validation

[gagbo]

Oh, and I forgot the sacred screenshot rule:

• Font is "FantasqueMonoSans"
• Colorscheme is one of the dark variants of "Rosé Pine" (forgot which one, but there are only 2 anyway)