Update pr_fetcher.py

pr_fetcher.py

@@ -1,13 +1,13 @@
 import requests
 
 def fetch_pr_diff(owner, repo, pr_number, token=None):
-    url = f"https://api.github.com/repos/{owner}/{repo}/pulls/{pr_number}"
     headers = {
         "Accept": "application/vnd.github.v3.diff"
     }
     if token:
         headers["Authorization"] = f"token {token}"
 
+    url = f"https://api.github.com/repos/{owner}/{repo}/pulls/{pr_number}"
     response = requests.get(url, headers=headers)
 
     if response.status_code == 200: