chore(internal): minor refactoring of client instantiation

Author: stainless-bot

src/finch/_client.py

@@ -89,7 +89,7 @@ def __init__(
         """
 
         if base_url is None:
-            base_url = "https://api.tryfinch.com"
+            base_url = f"https://api.tryfinch.com"
 
         super().__init__(
             version=__version__,
@@ -310,7 +310,7 @@ def __init__(
         """
 
         if base_url is None:
-            base_url = "https://api.tryfinch.com"
+            base_url = f"https://api.tryfinch.com"
 
         super().__init__(
             version=__version__,