systemd/{postmarketos-base-systemd,systemd-services}: fix maintainer line

abuild doesn't allow multiple "maintainer" lines, I should have used
Co-maintainer instead...

[ci:skip-vercheck]

extra-repos/systemd/postmarketos-base-systemd/APKBUILD

 # Maintainer: Oliver Smith <ollieparanoid@postmarketos.org>
-# Maintainer: Clayton Craft <clayton@craftyguy.net>
+# Co-maintainer: Clayton Craft <clayton@craftyguy.net>
 # pmbootstrap installs this, if systemd is selected in "pmbootstrap init".
 pkgname=postmarketos-base-systemd
 pkgver=24

extra-repos/systemd/systemd-services/APKBUILD

 # Maintainer: Caleb Connolly <caleb@connolly.tech>
-# Maintainer: Clayton Craft <clayton@craftyguy.net>
+# Co-maintainer: Clayton Craft <clayton@craftyguy.net>
 # Service files for projects that would otherwise either
 # need to be forked just for the service, or don't provide
 # a service file at all.