Fix return annotations of several methods that return self at runtime (#7070)

stdlib/ssl.pyi

@@ -396,7 +396,7 @@ class SSLContext:
     if sys.version_info >= (3, 8):
         keylog_filename: str
         post_handshake_auth: bool
-    def __new__(cls, protocol: int = ..., *args: Any, **kwargs: Any) -> SSLContext: ...
+    def __new__(cls: type[Self], protocol: int = ..., *args: Any, **kwargs: Any) -> Self: ...
     def __init__(self, protocol: int = ...) -> None: ...
     def cert_store_stats(self) -> dict[str, int]: ...
     def load_cert_chain(