Include pkgrel in the local source filename

Artifact rebuilds (e.g. dependency bundling) change the file behind
<pkg>-<ver>.tar.zst while keeping its name, so users with the previous
file in their AUR helper cache hit a checksum mismatch. Naming the local
download <pkg>-<ver>-<rel>.tar.zst makes every rebuild a fresh file.

trayscale-bin/PKGBUILD

@@ -13,7 +13,7 @@ depends=('gtk4' 'libadwaita' 'hicolor-icon-theme')
 optdepends=('tailscale: provides the daemon that manages the connection')
 provides=('trayscale')
 conflicts=('trayscale')
-source=("https://github.com/Felitendo/PKGBUILDS/releases/download/${pkgname}-${pkgver}/${pkgname}-${pkgver}.tar.zst")
+source=("${pkgname}-${pkgver}-${pkgrel}.tar.zst::https://github.com/Felitendo/PKGBUILDS/releases/download/${pkgname}-${pkgver}/${pkgname}-${pkgver}.tar.zst")
 sha256sums=('1b24f332a64a682e972e94fecfc11a7d719a1c74c5fd897c45c08cbd17d0ae93')
 
 package() {