A federal appeals court Monday declined to revive a lawsuit accusing Caterpillar Inc. of discriminating against older workers with a plan to end an unemployment-benefit program.The 7th U.S. Circuit Court of Appeals conceded the plan to liquidate a $7.8 million fund and distribute the money to certain employees at Caterpillar’s manufacturing facility in Joliet had a disparate impact on older workers.The liquidation plan treated employees who had participated in the unemployment program differently depending on a …