Revert "genRSAAndEd25519KeyPairではキーを直列に生成する?"

This reverts commit d0aada5.

packages/backend/src/misc/gen-key-pair.ts

@@ -6,8 +6,7 @@
 import { genEd25519KeyPair, genRsaKeyPair } from '@misskey-dev/node-http-message-signatures';
 
 export async function genRSAAndEd25519KeyPair(rsaModulusLength = 4096) {
-	const rsa = await genRsaKeyPair(rsaModulusLength);
-	const ed25519 = await genEd25519KeyPair();
+	const [rsa, ed25519] = await Promise.all([genRsaKeyPair(rsaModulusLength), genEd25519KeyPair()]);
 	return {
 		publicKey: rsa.publicKey,
 		privateKey: rsa.privateKey,