main/quagga: fix upstream source

Quagga is no longer hosted on savannah.gnu.org.

main/quagga/APKBUILD

@@ -15,7 +15,7 @@ install="$pkgname.pre-install $pkgname.post-install $pkgname.post-upgrade"
 subpackages="$pkgname-dev $pkgname-doc $pkgname-dbg $pkgname-openrc"
 pkgusers="quagga"
 pkggroups="quagga"
-source="https://download.savannah.gnu.org/releases/quagga/quagga-$pkgver.tar.gz
+source="https://github.com/Quagga/quagga/releases/download/quagga-$pkgver/quagga-$pkgver.tar.gz
 	0001-nhrpd-change-ipsec-SA-count-to-32-bit.patch
 	1001-bgpd-allow-using-ebgp-multihop-for-ibgp-connections.patch
 	dont-hook-core-signals.patch