doc: Client fetch API has deprecated synchronous context manager (#1801)

changes/1801.doc.md

@@ -0,0 +1 @@
+Update docstrings in `ai.backend.client.request.Request:fetch()` and `ai.backend.client.request.FetchContextManager` as the support for synchronous context manager has been deprecated.

src/ai/backend/client/request.py

@@ -296,18 +296,8 @@ def fetch(self, **kwargs) -> FetchContextManager:
         """
         Sends the request to the server and reads the response.
 
-        You may use this method either with plain synchronous Session or
-        AsyncSession.  Both the followings patterns are valid:
-
-        .. code-block:: python3
-
-          from ai.backend.client.request import Request
-          from ai.backend.client.session import Session
-
-          with Session() as sess:
-            rqst = Request('GET', ...)
-            with rqst.fetch() as resp:
-              print(resp.text())
+        You may use this method with AsyncSession only,
+        following the pattern below:
 
         .. code-block:: python3
 
@@ -538,7 +528,7 @@ class FetchContextManager:
     """
     The context manager returned by :func:`Request.fetch`.
 
-    It provides both synchronous and asynchronous context manager interfaces.
+    It provides asynchronous context manager interfaces only.
     """
 
     __slots__ = (