Hatchet: SSRF via Unsigned UnsubscribeURL in SNS UnsubscribeConfirmation Handler

Summary The SNS UnsubscribeConfirmation handler in internal/integrations/ingestors/sns/sns.go makes an unvalidated http.Get call to payload.UnsubscribeURL without any URL restriction. Because UnsubscribeURL is intentionally excluded from the BuildSignature signed field list, an attacker can repla...