gradle.properties: download natives snapshots from the MinIO instance

gradle.properties

@@ -46,4 +46,4 @@ POM_INCEPTION_YEAR=2009
 bintray_user=
 bintray_api_key=
 
-PREBUILD_NATIVES_URL=https://dl.bintray.com/jmonkeyengine/files/${natives.snapshot}/jme3-natives.zip
+PREBUILD_NATIVES_URL=https://objects.jmonkeyengine.org/native-snapshots/${natives.snapshot}/jme3-natives.zip