[socket] Revert adding proto default value in SocketType (#14549)

Author: donBarbos

stdlib/_socket.pyi

@@ -743,10 +743,10 @@ class socket:
     def timeout(self) -> float | None: ...  # noqa: F811
     if sys.platform == "win32":
         def __init__(
-            self, family: int = ..., type: int = ..., proto: int = 0, fileno: SupportsIndex | bytes | None = None
+            self, family: int = ..., type: int = ..., proto: int = ..., fileno: SupportsIndex | bytes | None = None
         ) -> None: ...
     else:
-        def __init__(self, family: int = ..., type: int = ..., proto: int = 0, fileno: SupportsIndex | None = None) -> None: ...
+        def __init__(self, family: int = ..., type: int = ..., proto: int = ..., fileno: SupportsIndex | None = None) -> None: ...
 
     def bind(self, address: _Address, /) -> None: ...
     def close(self) -> None: ...