ecc: use p256::NistP256

[lispc]

No description provided.

[github-actions]

group	app.proof_time_ms	app.cycles	app.cells_used	leaf.proof_time_ms	leaf.cycles	leaf.cells_used
verify_fibair	(+15 [+1.1%]) 1,364	143,574	8,290,093	-	-	-
fibonacci_program	(-8 [-0.2%]) 4,916	1,500,095	51,485,080	-	-	-
regex_program	(-20 [-0.1%]) 13,839	4,139,840	165,455,373	-	-	-
ecrecover_program	(-38 [-1.5%]) 2,458	284,567	15,055,723	-	-	-

Commit: 7c63d20

Benchmark Workflow