fix(observe): set Accept-Encoding header when fetching arns data

Gateways may use CDNs to serve data. Those CDN's may return compressed data depending on their configuration. To avoid discrpencies, the observations should request the raw data  using the `Accept-Encoding: identity` header. 

Related PR: ar-io/ar-io-observer#53

src/utils/index.ts

@@ -104,6 +104,10 @@ export const fetchWithTimeout = async (resource:string, options?:RequestInit, ti
 
   const response = await fetch(resource, {
     ...options,
+    headers: {
+      ...options?.headers,
+      'Accept-Encoding': 'identity'
+    },
     signal: controller.signal  
   });
   clearTimeout(id);