Revert "PYTHON-5543 PyMongoBaseProtocol should inherit from asyncio.BaseProtocol (mongodb#2528)"

This reverts commit 3da6e85.

Author: blink1073

doc/changelog.rst

@@ -1,14 +1,6 @@
 Changelog
 =========
 
-Changes in Version 4.15.1 (XXXX/XX/XX)
---------------------------------------
-
-Version 4.15.1 is a bug fix release.
-
-- Fixed a bug in ``AsyncMongoClient`` that caused a
-  ``ServerSelectionTimeoutError`` when used with ``uvicorn``, ``FastAPI``, or ``uvloop``.
-
 Changes in Version 4.15.0 (2025/09/10)
 --------------------------------------
 

pymongo/network_layer.py

@@ -22,7 +22,7 @@
 import struct
 import sys
 import time
-from asyncio import BaseProtocol, BaseTransport, BufferedProtocol, Future, Transport
+from asyncio import BaseTransport, BufferedProtocol, Future, Protocol, Transport
 from typing import (
     TYPE_CHECKING,
     Any,
@@ -250,7 +250,7 @@ def recv_into(self, buffer: bytes | memoryview) -> int:
         return self.conn.recv_into(buffer)
 
 
-class PyMongoBaseProtocol(BaseProtocol):
+class PyMongoBaseProtocol(Protocol):
     def __init__(self, timeout: Optional[float] = None):
         self.transport: Transport = None  # type: ignore[assignment]
         self._timeout = timeout