SPRINGFIELD — After weeks of speculation, Gov. Bruce Rauner has approved a law making it tougher to detain people based solely on their immigration status.The Republican governor this morning signed Senate Bill 31, which prohibits local and state police from detaining people without a judge’s consent. The measure was set to become law automatically today if Rauner didn’t act.Rauner was effusive in his praise for immigrants, police and the bill at a signing ceremony in Chicago this morning, calling police  …