From @aron in #259 (comment)
We should cover what to do if your environment doesn't support Request, in which case you pass through the parts manually:
const requestData = {
id: "123", // the `Webhook-Id` header
timestamp: 0123456, // the `Webhook-Timestamp` header
signature: "xyz", // the `Webhook-Signature` header
body: "", // the request body as a string, ArrayBuffer or ReadableStream
};
const webhookIsValid = await validateWebhook(requestData, secret);