setSecret not updating $config

[salmanalee]

If you are using multiple secrets and you were previously using setSecret(), it has stopped working. setSecret method should also update existing $config->signingKey.

e232940#diff-38952bbf39362840adfc497a8b590ee232d2c5812c9eb340220159eb42463590L73

Previously, it was using payload keys so updating $secret was working

e232940#diff-38952bbf39362840adfc497a8b590ee232d2c5812c9eb340220159eb42463590L73

Expected Behaviour: When calling setSecret, it should update $config->signingKey also or there should be a way to call buildConfig from