Simplify source entry by reusing url

Signed-off-by: David Runge <dvzrv@archlinux.org>

PKGBUILD

@@ -15,7 +15,7 @@ depends=(
 )
 makedepends=(perl)
 provides=(libprrte.so)
-source=($pkgname-$pkgver.tar.gz::https://github.com/openpmix/$pkgname/releases/download/v$pkgver/$pkgname-$pkgver.tar.gz)
+source=($pkgname-$pkgver.tar.gz::$url/releases/download/v$pkgver/$pkgname-$pkgver.tar.gz)
 sha512sums=('3400f666092531f0f55054fefe0f28aaa94b177f170ad038f3f87a9c62b1fe4139fdde480030afb7eb0147b4775fdd83742424ccb4306234343e244f089935d6')
 b2sums=('d4899e08c5ee2766d61fa56d53cd9ecdc9e3c16cb9328476c1d18e7bb65058b57a9d243f5540e15057b1fb6fb4c5d097c869c778a69f525441b6b63778a17038')