BILLINGS, Mont. - Attorneys general from 21 states on Wednesday sued to overturn President Joe Biden’s cancellation of the contentious Keystone XL oil pipeline from Canada.Led by Ken Paxton of Texas and Austin Knudsen of Montana, the states said Biden had overstepped his authority when he revoked the permit for the Keystone pipeline on his first day in office.RELATED: Keystone XL oil pipeline construction stops as Biden moves to revoke permitBecause the line would run through multiple U.S.