Remove stubtest allowlist entry

Author: srittau

stdlib/@tests/stubtest_allowlists/common.txt

@@ -237,7 +237,6 @@ asyncio.locks.Condition.release
 builtins.memoryview.__contains__  # C type that implements __getitem__
 builtins.reveal_locals  # Builtins that type checkers pretends exist
 builtins.reveal_type  # Builtins that type checkers pretends exist
-builtins.type.__dict__  # read-only but not actually a property; stubtest thinks it's a mutable attribute.
 
 # The following CodecInfo properties are added in __new__
 codecs.CodecInfo.decode