Use space instead of tab in config file [ci skip]

PeterDaveHello · PeterDaveHello · commit 2bd706730e40 · 2018-06-27T19:47:48.000+08:00
diff --git a/config b/config
@@ -1,3 +1,3 @@
 baseuri     https://nodejs.org/dist
-default_variant	jessie
+default_variant jessie
 alpine_version  3.7
