xiaomi-laurel: Set pkgrel back to 0

Internally I increased the pkgrel to build new versions of the same
package. However, now that device-xiaomi-laurel is going on pmaports,
aports-static recommends setting it back to 0.

device/testing/device-xiaomi-laurel/APKBUILD

@@ -2,7 +2,7 @@
 pkgname=device-xiaomi-laurel
 pkgdesc="Xiaomi Mi A3"
 pkgver=0.1
-pkgrel=3
+pkgrel=0
 url="https://postmarketos.org"
 license="MIT"
 arch="aarch64"