examples: Use urllib3 in client example

This is in order to not clash with theupdateframework#2762.

Signed-off-by: Jussi Kukkonen <[email protected]>

examples/client/client

@@ -12,7 +12,7 @@ import traceback
 from hashlib import sha256
 from pathlib import Path
 
-import requests
+import urllib3
 
 from tuf.api.exceptions import DownloadError, RepositoryError
 from tuf.ngclient import Updater
@@ -41,13 +41,17 @@ def init_tofu(base_url: str) -> bool:
     if not os.path.isdir(metadata_dir):
         os.makedirs(metadata_dir)
 
-    data = requests.get(f"{base_url}/metadata/1.root.json").content
+    response = urllib3.request("GET", f"{base_url}/metadata/1.root.json")
+    if response.status != 200:
+        print(f"Failed to download initial root {base_url}/metadata/1.root.json")
+        return False
+
     Updater(
         metadata_dir=metadata_dir,
         metadata_base_url=f"{base_url}/metadata/",
         target_base_url=f"{base_url}/targets/",
         target_dir=DOWNLOAD_DIR,
-        bootstrap=data,
+        bootstrap=response.data,
     )
 
     print(f"Trust-on-First-Use: Initialized new root in {metadata_dir}")