Add missing type hints in http.client (#5734)

* Add missing type hints in http.client

* Add http.client.HTTPConnection.response_class to exclude list

stdlib/http/client.pyi

@@ -90,7 +90,8 @@ NETWORK_AUTHENTICATION_REQUIRED: int
 
 responses: Dict[int, str]
 
-class HTTPMessage(email.message.Message): ...
+class HTTPMessage(email.message.Message):
+    def getallmatchingheaders(self, name: str) -> list[str]: ...  # undocumented
 
 def parse_headers(fp: io.BufferedIOBase, _class: Callable[[], email.message.Message] = ...) -> HTTPMessage: ...
 
@@ -103,6 +104,7 @@ class HTTPResponse(io.BufferedIOBase, BinaryIO):
     status: int
     reason: str
     def __init__(self, sock: socket, debuglevel: int = ..., method: Optional[str] = ..., url: Optional[str] = ...) -> None: ...
+    def peek(self, n: int = ...) -> bytes: ...
     def read(self, amt: Optional[int] = ...) -> bytes: ...
     def read1(self, n: int = ...) -> bytes: ...
     def readinto(self, b: WriteableBuffer) -> int: ...
@@ -142,6 +144,10 @@ class _HTTPConnectionProtocol(Protocol):
         ) -> HTTPConnection: ...
 
 class HTTPConnection:
+    auto_open: int = ...  # undocumented
+    debuglevel: int = ...
+    default_port: int = ...  # undocumented
+    response_class: Type[HTTPResponse] = ...  # undocumented
     timeout: Optional[float]
     host: str
     port: int

tests/stubtest_allowlists/py3_common.txt

@@ -88,6 +88,7 @@ enum.EnumMeta.__call__
 enum.EnumMeta.__new__
 http.HTTPStatus.description  # set in __new__
 http.HTTPStatus.phrase  # set in __new__
+http.client.HTTPConnection.response_class  # the actual type at runtime is abc.ABCMeta
 imaplib.IMAP4_SSL.ssl  # Dependent on SSL existence
 importlib.abc.FileLoader.get_filename  # Wrapped with _check_name decorator which changes runtime signature
 importlib.abc.FileLoader.load_module  # Wrapped with _check_name decorator which changes runtime signature