Close TarIO file handle on error

[radarhere]

When testing TarIO errors, the file handle is not closed - https://github.com/python-pillow/Pillow/actions/runs/14155530774/job/39654267057?pr=8844#step:6:5611

Tests/test_file_tar.py::test_unexpected_end
  /Pillow/Tests/test_file_tar.py:38: ResourceWarning: unclosed file <_io.BufferedReader name='/tmp/pytest-of-pillow/pytest-0/test_unexpected_end0/temp.tar'>
    with pytest.raises(OSError, match="unexpected end of tar file"):
  Enable tracemalloc to get traceback where the object was allocated.
  See https://docs.pytest.org/en/stable/how-to/capture-warnings.html#resource-warnings for more info.

Tests/test_file_tar.py::test_cannot_find_subfile
  /Pillow/Tests/test_file_tar.py:44: ResourceWarning: unclosed file <_io.BufferedReader name='Tests/images/hopper.tar'>
    with pytest.raises(OSError, match="cannot find subfile"):
  Enable tracemalloc to get traceback where the object was allocated.
  See https://docs.pytest.org/en/stable/how-to/capture-warnings.html#resource-warnings for more info.

This fixes that.