Removed a bunch of unused import symbols detected by pyright. (#5060)

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

stubs/simplejson/simplejson/decoder.pyi

@@ -1,6 +1,6 @@
-from typing import Match
+from typing import Any, Match
 
 class JSONDecoder(object):
-    def __init__(self, **kwargs): ...
+    def __init__(self, **kwargs: Any) -> None: ...
     def decode(self, s: str, _w: Match[str], _PY3: bool): ...
     def raw_decode(self, s: str, idx: int, _w: Match[str], _PY3: bool): ...