fix: update staging email url

this is why the integration tests are failing! I failed to update the link when I deployed the D1 migration work, so the auth flow never actually completes. DOH.

test/helpers/up-client.js

@@ -17,7 +17,7 @@ function getAuthLinkFromEmail (email, uploadServiceUrl) {
   const link = email.match(/<a href="([^"]*)".*Verify email address/)[1]
 
   // test auth services always link to the staging URL but we want to hit the service we're testing
-  return link.replace("https://w3access-staging.protocol-labs.workers.dev", uploadServiceUrl)
+  return link.replace("https://staging.up.web3.storage", uploadServiceUrl)
 }
 
 async function createMailSlurpInbox() {