fix(circuits): use dynamic imports for promisify

packages/circuits/ts/compile.ts

@@ -3,12 +3,9 @@ import { type CircomkitConfig, type CircuitConfig, Circomkit } from "circomkit";
 import childProcess from "child_process";
 import fs from "fs";
 import path from "path";
-import { promisify } from "util";
 
 import type { CircuitConfigWithName } from "./types";
 
-const execFile = promisify(childProcess.execFile);
-
 /**
  * Compile MACI's circuits using circomkit
  * and setup the dir structure
@@ -51,6 +48,9 @@ export const compileCircuits = async (cWitness?: boolean, outputPath?: string):
     verbose: false,
   });
 
+  const { promisify } = await import("util");
+  const execFile = promisify(childProcess.execFile);
+
   // loop through each circuit config and compile them
   // eslint-disable-next-line @typescript-eslint/prefer-for-of
   for (let i = 0; i < circuitsConfigs.length; i += 1) {

packages/circuits/ts/proofs.ts

@@ -5,15 +5,12 @@ import childProcess from "child_process";
 import fs from "fs";
 import { tmpdir } from "os";
 import path from "path";
-import { promisify } from "util";
 
 import type { IGenProofOptions, ISnarkJSVerificationKey, FullProveResult } from "./types";
 import type { IVkObjectParams } from "maci-domainobjs";
 
 import { cleanThreads, isArm } from "./utils";
 
-const execFile = promisify(childProcess.execFile);
-
 /**
  * Generate a zk-SNARK proof
  * @dev if running on a intel chip we use rapidsnark for
@@ -70,6 +67,9 @@ export const genProof = async ({
   const jsonData = JSON.stringify(stringifyBigInts(inputs));
   await fs.promises.writeFile(inputJsonPath, jsonData);
 
+  const { promisify } = await import("util");
+  const execFile = promisify(childProcess.execFile);
+
   // Generate the witness
   await execFile(witnessExePath!, [inputJsonPath, outputWtnsPath]);