Add federation self-testing

vona/globals/__init__.py

@@ -4,11 +4,13 @@ import nacl.signing
 import hashlib
 import base64
 import random
+import httpx
 import copy
 import json
 import re
 
 version = "1.4.2"
+http_client = httpx.Client(headers={"User-Agent": f"Vona/{version}"})
 
 
 def canonical_json(value):