Add optional Headers param to fetchChain (#4793)

### TL;DR

Added an optional Headers parameter to the `fetchChain` function.

### What changed?

- Introduced a new optional `headers` parameter to the `fetchChain` function in `apps/dashboard/src/utils/fetchChain.ts`.
- Updated the fetch request to include the provided headers.
- Created a new changeset file to document this patch-level change.

### How to test?

1. Call the `fetchChain` function without providing headers to ensure backward compatibility.
2. Call the `fetchChain` function with custom headers and verify they are included in the request.
3. Confirm that the function still correctly fetches chain metadata from the API.

### Why make this change?

This change allows for greater flexibility when making API requests to fetch chain metadata. By allowing custom headers, it enables use cases such as authentication, caching control, or other custom requirements when interacting with the API.

.changeset/two-rings-compare.md

@@ -0,0 +1,5 @@
+---
+"thirdweb": patch
+---
+
+add optional Headers param to `fetchChain`

apps/dashboard/src/utils/fetchChain.ts

@@ -2,11 +2,15 @@ import type { ChainMetadata } from "thirdweb/chains";
 
 export async function fetchChain(
   chainIdOrSlug: string | number,
+  headers = new Headers(),
 ): Promise<ChainMetadata | null> {
   // always fetch from prod for chains for now
   // TODO: re-visit this
   const res = await fetch(
     `https://api.thirdweb.com/v1/chains/${chainIdOrSlug}`,
+    {
+      headers,
+    },
   );
   if (res.ok) {
     try {