Update client.py

Author: Beesonn

mango/client.py

@@ -45,7 +45,7 @@ def _do_request(self, endpoint: str, method: str = "GET", json: dict = None):
         Raises:
             MangoError subclasses depending on failure type.
         """
-        url = f"{self.base_url}/{endpoint}"
+        url = f"{self.base_url}{endpoint}"
 
         try:
             response = self.session.request(