Add accepts method stub in HttpRequest (#676)

* Add accepts method to HttpRequest stubs

The accepts method (and dependencies) was missing in the stub for HttpRequest

* Change accepted_types to return correct type

* Fix Black formatting

* Add annotation for MediaType __init__ args

django-stubs/http/request.pyi

@@ -70,7 +70,8 @@ class HttpRequest(BytesIO):
     def scheme(self) -> Optional[str]: ...
     def is_secure(self) -> bool: ...
     def is_ajax(self) -> bool: ...
-    def accepted_types(self) -> str: ...
+    @property
+    def accepted_types(self) -> List[MediaType]: ...
     def __repr__(self) -> str: ...
     def parse_file_upload(
         self, META: Mapping[str, Any], post_data: BinaryIO
@@ -80,6 +81,7 @@ class HttpRequest(BytesIO):
     @property
     def body(self) -> bytes: ...
     def _load_post_and_files(self) -> None: ...
+    def accepts(self, media_type: str) -> bool: ...
 
 _Q = TypeVar("_Q", bound="QueryDict")
 
@@ -102,6 +104,12 @@ class QueryDict(MultiValueDict[str, str]):
         encoding: Optional[str] = ...,
     ) -> _Q: ...
 
+class MediaType:
+    def __init__(self, media_type_raw_line: str) -> None: ...
+    @property
+    def is_all_types(self) -> bool: ...
+    def match(self, other) -> bool: ...
+
 @overload
 def bytes_to_text(s: bytes, encoding: str) -> str: ...
 @overload