uses a for of instead of Object.fromEntries to preserve arrays in hea…

…ders

This is necessary because the only way to set multiple cookies reliably from node is by writing a header like this:
'set-cookie': ['foo=bar', 'bar=baz']. Using Object.entries serializes the Array into a string which is not
what we want.

.changeset/fuzzy-jeans-tickle.md

@@ -0,0 +1,5 @@
+---
+'@shopify/hydrogen': patch
+---
+
+Adds ability to add multiple cookies in one response

packages/hydrogen/src/entry-server.tsx

@@ -819,7 +819,10 @@ function getResponseOptions(
 ) {
   const responseInit = {} as ResponseOptions;
   // @ts-ignore
-  responseInit.headers = Object.fromEntries(headers.entries());
+  for (const key of headers.keys()) {
+    // @ts-ignore
+    responseInit.headers[key] = headers.raw()[key];
+  }
 
   if (error) {
     responseInit.status = 500;