Fix credentials configuration in preLoading.st

Workaround for hpi-swa/smalltalkCI#485 and Metacello/metacello#524.

Author: LinqLover

scripts/preLoading.st

@@ -1 +1,5 @@
+"Workaround for https://github.com/hpi-swa/smalltalkCI/pull/485 and https://github.com/Metacello/metacello/issues/524"
+Installer new installSAR: 'metacello.sar' from: (WebClient httpGet: 'http://forum.world.st/attachment/5121139/0/metacello.sar') content asByteArray readStream.
+
+"Actual credentials configuration"
 MCFetchGithubRepository sitePassword: (SmalltalkCI getEnv: 'GITHUB_TOKEN').