Revert "Fix zip file for 2.3.1 doesn't exist #137"

This reverts commit 7273ef7afe2f43b58a299baf7fa74ef54754a628.

compose/magento-2/bin/download

@@ -1,4 +1,3 @@
 #!/bin/bash
 [ -z "$1" ] && echo "Please specify the version to download (ex. 2.0.0)" && exit
-mkdir -p src && curl -L https://github.com/magento/magento2/archive/$1.tar.gz | tar xzf - -o
-rm -rf src && mv magento2-$1 src
+mkdir -p src && curl -L http://pubfiles.nexcess.net/magento/ce-packages/magento2-$1.tar.gz | tar xzf - -o -C src