purism-librem5dev: archive (MR 6000)

This is the port for the Librem 5 devkit, I still have one but haven't
booted it in years and it's unlikely anyone else is using this (since
this port is super outdated and almost certainly not functional as-is).
Let's archive it so that it doesn't cause any confusion.

[ci:skip-vercheck]
[ci:skip-build]: we don't actually want to build test this thing

device/testing/device-purism-librem5dev/APKBUILD → device/archived/device-purism-librem5dev/APKBUILD

 # Reference: <https://postmarketos.org/devicepkg>
-# Maintainer: Clayton Craft <clayton@craftyguy.net>
+# Archived: Not actively maintained, hw is very rare/unlikely to be used by anyone, and port is outdated/broken
 pkgname=device-purism-librem5dev
 pkgdesc="Purism Librem 5 Devkit"
 pkgver=2