The Big Sky Conference does not have to face a proposed class-action lawsuit in Chicago federal court accusing it of failing to protect student-athletes who suffered concussions.In a written opinion last week, U.S. District Judge John Z. Lee did not rule on the merits of allegations that Big Sky did not follow proper procedures to prevent and treat concussions when plaintiff Eric Weston played football for Weber State University in Utah.Instead, Lee held Big Sky does not have enough contacts with Indiana — the state where …