The 7th U.S. Circuit Court of Appeals revived a class-action lawsuit filed by two people who were sent fines by a collection agency after allegedly failing to pay $1.50 parking fees at a South Side Metra commuter lot.In an opinion written by Judge Diane S. Sykes, the panel reversed a district judge’s summary judgment in the collector’s favor, instead ruling that money owed to the operator of a parking lot is contractual debt — not a legislative-endorsed fine — and therefore is subject to the federal …