`XDG_CONFIG_HOME` points to `/home/runneradmin/.config`, not `/home/runner/.config`

[mhils]

In the Ubuntu 24.04 ARM64 image, the $XDG_CONFIG_HOME environment variable currently points to a directory that's not readable by the current user. This causes issues for software that tries to read configuration from disk. For example, cargo fails if build.rs is present because it then tries to read git configuration and fails to access it.

Workaround: Overwrite XDG_CONFIG_HOME for the failing CI step, for example like this:

     - run: ...
       env:
         XDG_CONFIG_HOME: ~/.config

[purplesyringa]

This applies to $PATH, too.