3 tests fail: AttributeError: type object 'reprec' has no attribute 'assertoutcome'

```
============================================================================== FAILURES ===============================================================================
____________________________________________________________________________ test_with_rst ____________________________________________________________________________

testdir = , testpackage = None

def test_with_rst(testdir, testpackage):
# Make sure all rst tests are also picked up when using pytest-doctestplus
testdir.makeini("""
[pytest]
doctest_plus = enabled
""")
reprec = testdir.inline_run('--doctest-rst')
> reprec.assertoutcome(passed=7, failed=3)
^^^^^^^^^^^^^^^^^^^^
E AttributeError: type object 'reprec' has no attribute 'assertoutcome'

/usr/ports/devel/py-pytest-filter-subpackage/work-py311/pytest-filter-subpackage-0.2.0/tests/test_filter_subpackage.py:17: AttributeError
------------------------------------------------------------------------ Captured stderr call -------------------------------------------------------------------------
ERROR: usage: __main__.py [options] [file_or_dir] [file_or_dir] [...]
__main__.py: error: unrecognized arguments: --doctest-rst
inifile: /tmp/pytest-of-yuri/pytest-54/test_with_rst0/tox.ini
rootdir: /tmp/pytest-of-yuri/pytest-54/test_with_rst0

________________________________________________________________ test_flag_single_subpackage_with_rst _________________________________________________________________

testdir = , testpackage = None

def test_flag_single_subpackage_with_rst(testdir, testpackage):
# Test -P with a single sub-package including rst files
testdir.makeini("""
[pytest]
doctest_plus = enabled
""")
reprec = testdir.inline_run('-P a', '--doctest-rst')
> reprec.assertoutcome(passed=3, failed=0)
^^^^^^^^^^^^^^^^^^^^
E AttributeError: type object 'reprec' has no attribute 'assertoutcome'

/usr/ports/devel/py-pytest-filter-subpackage/work-py311/pytest-filter-subpackage-0.2.0/tests/test_filter_subpackage.py:33: AttributeError
------------------------------------------------------------------------ Captured stderr call -------------------------------------------------------------------------
ERROR: usage: __main__.py [options] [file_or_dir] [file_or_dir] [...]
__main__.py: error: unrecognized arguments: --doctest-rst
inifile: /tmp/pytest-of-yuri/pytest-54/test_flag_single_subpackage_with_rst0/tox.ini
rootdir: /tmp/pytest-of-yuri/pytest-54/test_flag_single_subpackage_with_rst0

_______________________________________________________________ test_flag_multiple_subpackage_with_rst ________________________________________________________________

testdir = , testpackage = None

def test_flag_multiple_subpackage_with_rst(testdir, testpackage):
# Test -P with several sub-packages including rst files
testdir.makeini("""
[pytest]
doctest_plus = enabled
""")
reprec = testdir.inline_run('-P a,b', '--doctest-rst')
> reprec.assertoutcome(passed=4, failed=1)
^^^^^^^^^^^^^^^^^^^^
E AttributeError: type object 'reprec' has no attribute 'assertoutcome'

/usr/ports/devel/py-pytest-filter-subpackage/work-py311/pytest-filter-subpackage-0.2.0/tests/test_filter_subpackage.py:49: AttributeError
------------------------------------------------------------------------ Captured stderr call -------------------------------------------------------------------------
ERROR: usage: __main__.py [options] [file_or_dir] [file_or_dir] [...]
__main__.py: error: unrecognized arguments: --doctest-rst
inifile: /tmp/pytest-of-yuri/pytest-54/test_flag_multiple_subpackage_with_rst0/tox.ini
rootdir: /tmp/pytest-of-yuri/pytest-54/test_flag_multiple_subpackage_with_rst0

===================================================================== 3 failed, 5 passed in 3.40s =====================================================================
*** Error code 1

```

Version: 0.2.0
Python-3.11
FreeBSD 14.3

Reproduce the failures in tests/test_filter_subpackage.py under Python 3.11, focusing on the testdir.inline_run calls using --doctest-rst. Check why the returned object lacks assertoutcome and why the option is rejected; done means the three affected tests run with the expected pass and failure counts.

Written by the indexing model from the issue text.