Fix: user/password replacement is not allowed for relative urls

fix error `user/password replacement is not allowed for relative URLs` when using the parameter base_url of ClientSession constructor to send aiohttp requests

Author: tsonglew

skywalking/plugins/sw_aiohttp.py

@@ -39,8 +39,16 @@ def install():
 
     _request = ClientSession._request
 
+    def _build_url(client_session: ClientSession, str_or_url):
+        url = URL(str_or_url)
+        if client_session._base_url is None:
+            return url
+        else:
+            assert not url.is_absolute() and url.path.startswith('/')
+            return client_session._base_url.join(url)
+
     async def _sw_request(self: ClientSession, method: str, str_or_url, **kwargs):
-        url = URL(str_or_url).with_user(None).with_password(None)
+        url = _build_url(self, str_or_url).with_user(None).with_password(None)
         peer = f"{url.host or ''}:{url.port or ''}"
 
         if config.agent_protocol == 'http' and config.agent_collector_backend_services.rstrip('/') \