Replaced parameter name "self" with "cls" for a few class methods (#4393)

* Replaced parameter name "self" with "cls" for a few class methods. Pyright emits a warning if a class method doesn't follow the PEP 8 standard where the first parameter is named "cls" for a class method. This change eliminates these warnings.

* Missed a file.

Co-authored-by: Eric Traut <erictr@microsoft.com>

third_party/2and3/boto/s3/bucket.pyi

@@ -7,7 +7,7 @@ from .key import Key
 class S3WebsiteEndpointTranslate:
     trans_region: Dict[str, str]
     @classmethod
-    def translate_region(self, reg: Text) -> str: ...
+    def translate_region(cls, reg: Text) -> str: ...
 
 S3Permissions: List[str]
 

third_party/2and3/pynamodb/indexes.pyi

@@ -10,7 +10,7 @@ class Index(metaclass=IndexMeta):
     def count(cls, hash_key, consistent_read: bool = ..., **filters) -> int: ...
     @classmethod
     def query(
-        self,
+        cls,
         hash_key,
         scan_index_forward: Optional[Any] = ...,
         consistent_read: bool = ...,