main/rp-pppoe: fix download url

Archive has been moved to a directory called 'OLD'

main/rp-pppoe/APKBUILD

@@ -9,7 +9,7 @@ arch="all"
 license="GPL-2.0-or-later"
 makedepends="ppp-dev linux-headers"
 subpackages="$pkgname-doc $pkgname-openrc"
-source="https://dianne.skoll.ca/projects/rp-pppoe/download/rp-pppoe-$pkgver.tar.gz
+source="https://dianne.skoll.ca/projects/rp-pppoe/download/OLD/rp-pppoe-$pkgver.tar.gz
 	musl-fix.patch
 	rp-pppoe.initd
 	"