Summary
Update the APT mirror list before the build.
When we build a binary in the vyos-build container.
The repository update process must be independent of the existence of package/package.toml dependencies.
Currently, if we do not have dependencies, we just skip this step https://github.com/vyos/vyos-build/blob/0dc2973568be1a05f55862325f4a3d972bb2915b/scripts/package-build/build.py#L31-L33
So run(['sudo', 'apt-get', 'update'], check=True) will never execute without [dependencies]
This may lead to build failures for certain packages.