device-purism-librem5: remove craftyguy as maintainer

I'm not able to give this device the attention it deserves.

FYI @Newbyte @alistair23

Edit: to those reacting with the sad emoji face thingy... don't be sad! I feel like there are enough folks stepping up to help maintain it and that they can handle it, so I can now go focus on other things. That's actually really great! 😁