systemd/systemd: bump pkgrel

In the previous commits,
- enabled bootloader support on 32-bit architectures,
- fixed libpwquality dependency,
- enabled libarchive and zlib supports,
- enabled xen kexec support,
- enabled valgrind support,
- added systemd-tests subpackage,
- added upstream build support.

So, let's bump the pkgrel to make them take effects.

Part-of: <https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/8718>

extra-repos/systemd/systemd-stage0/APKBUILD

@@ -6,7 +6,7 @@ pkgname=systemd-stage0
 pkgver=261_rc3
 _pkgver="${pkgver/_/-}"
 # pkgrel must match systemd!
-pkgrel=2
+pkgrel=3
 pkgdesc="Minimal systemd bootstrap package"
 url="https://github.com/systemd/systemd"
 # armhf: pmb#2618

extra-repos/systemd/systemd/APKBUILD

@@ -17,7 +17,7 @@ pkgname=systemd
 pkgver=261_rc3
 _pkgver="${pkgver/_/-}"
 # pkgrel must match systemd-stage0!
-pkgrel=2
+pkgrel=3
 pkgdesc="System and service manager"
 url="https://github.com/systemd/systemd"
 # armhf: no linux-stable