Use GitHub pages URLs for public channel JSONs

stub/build.gradle.kts

@@ -3,11 +3,14 @@ plugins {
 }
 
 android {
+    val canary = !Config["appVersion"].orEmpty().contains(".")
+
     defaultConfig {
         applicationId = "com.topjohnwu.magisk"
         versionCode = 1
         versionName = Config["appVersion"]
         buildConfigField("String", "DEV_CHANNEL", Config["DEV_CHANNEL"] ?: "null")
+        buildConfigField("boolean", "CANARY", if (canary) "true" else "false")
     }
 
     buildTypes {