Update to use the newest bootloader crate version

[wooster0]

I think it would be nice to update the steps on https://os.phil-opp.com/minimal-rust-kernel to use the newest version 0.10.1 of the bootloader crate which, as of 0.10.0, no longer uses the bootimage crate. This might make some things easier or more lightweight. The steps don't currently work for >0.9.16.

Also, https://os.phil-opp.com/minimal-rust-kernel/#real-machine says

the bootloader crate has no UEFI support yet.

but https://github.com/rust-osdev/bootloader#bootloader says otherwise.

[phil-opp]

I'm already working on it (in the edition-3) branch. This "3rd edition" will come with a few other differences, e.g. using a pixel-based framebuffer instead of the VGA text mode.