WASHINGTON — A federal appeals court in Virginia this week delivered a message to Congress, the White House and developers of the Mountain Valley Pipeline: not so fast. Pennsylvania-based Equitrans Midstream’s roughly 300-mile pipeline, envisioned to bring shale gas from the Marcellus and Utica in Appalachia to markets in the Southeast, was fast-tracked as part of the Biden administration’s deal with Congress to suspend the debt limit in June. It’s also supported by Pennsylvania congressmen, including U.S. Reps. John Joyce, R-Blair, and Guy Reschenthaler, R-Peters, who joined U.S. Rep. Carol Miller, R-W.Va., to introduce the legislation in May that helped...