Incorrect type annotation of `tarfile.Tarfile.fileobj`

[emontnemery]

tarfile.Tarfile.fileobj is incorrectly typed as _Fileobj | None, the correct type is _Fileobj

typeshed/stdlib/tarfile.pyi

Line 122 in 11ff7e1

fileobj: _Fileobj | None

Looking back at the history, it seems this was introduced when tarfile was first added to typeshed in #467

For reference, tarfile.Tarfile.fileobj is unconditionally set to a _Fileobj in the tarfile.Tarfile constructor, and never set anywhere else: https://github.com/python/cpython/blob/93b27e7f6d185efd5163d04fcdae8436ebf69144/Lib/tarfile.py#L1743-L1758

[srittau]

Thanks for the reference. PR welcome!

[emontnemery]

PR: #15367
I double checked other level attributes, and it turns out most of the attributes marked as optional are not optional. I change those in the same PR.

[srittau]

Fixed by #15367.