ModuleNotFoundError: No module named 'tomllib'

Describe the bug When I run tests in Travis CI against Python3.11-dev I get the following error:

$ coverage run --branch pedantic/tests/tests_main.py

Traceback (most recent call last):

  File "/home/travis/virtualenv/python3.11-dev/bin/coverage", line 5, in <module>

    from coverage.cmdline import main

    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

  File "/home/travis/virtualenv/python3.11-dev/lib/python3.11/site-packages/coverage/__init__.py", line 15, in <module>

    from coverage.control import Coverage, process_startup

    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

  File "/home/travis/virtualenv/python3.11-dev/lib/python3.11/site-packages/coverage/control.py", line 20, in <module>

    from coverage.collector import Collector, CTracer

    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

  File "/home/travis/virtualenv/python3.11-dev/lib/python3.11/site-packages/coverage/collector.py", line 10, in <module>

    from coverage.config import CoverageConfig

    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

  File "/home/travis/virtualenv/python3.11-dev/lib/python3.11/site-packages/coverage/config.py", line 16, in <module>

    from coverage.tomlconfig import TomlConfigParser, TomlDecodeError

    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

  File "/home/travis/virtualenv/python3.11-dev/lib/python3.11/site-packages/coverage/tomlconfig.py", line 16, in <module>

    import tomllib      # pylint: disable=import-error

    ^^^^^^^^^^^^^^

ModuleNotFoundError: No module named 'tomllib'

To Reproduce How can we reproduce the problem? Please be specific. Don’t link to a failing CI job. Answer the questions below:

1. What version of Python are you using? Python 3.11.0a3+
2. What version of coverage.py shows the problem? 6.4
3. What code shows the problem? Does not matter.
4. What commands did you run? coverage run --branch pedantic/tests/tests_main.py

Expected behavior Run tests with coverage.

Additional context Nothing.