fix(blevm): groth16 instead of core proofs (#127)

As the error message suggests, switching to groth16 proofs fixed the
issue:

> Error: status: InvalidArgument, message: "core proofs above 5000000
cycles are not supported - please request a compressed, groth16, or
plonk proof instead", details: [], metadata: MetadataMap { headers:
{"server": "awselb/2.0", "date": "Wed, 29 Jan 2025 06:32:45 GMT",
"content-type": "application/grpc", "content-length": "0",
"access-control-allow-origin": "*", "vary": "origin,
access-control-request-method, access-control-request-headers"} }


Fixes #113

provers/blevm/blevm-prover/src/lib.rs

@@ -224,7 +224,7 @@ impl BlockProver {
         // Generate and return the proof
         let client = ProverClient::from_env();
         let (pk, _) = client.setup(self.prover_config.elf_bytes);
-        let proof = client.prove(&pk, &stdin).core().run()?;
+        let proof = client.prove(&pk, &stdin).groth16().run()?;
 
         bincode::serialize(&proof).map_err(|e| e.into())
     }