Remove workaround in pyproject.toml once pyproject-parser 0.9 is out

[apirogov]

repo-helper/pyproject-parser#47

Once 0.9 is out, it should be picked up when installing codemetapy, which has no version bound set, so it should pull the newest version and not hit the current problem.

[apirogov]

econchick/interrogate#153

Now need to wait for interrogate to be fixed too, and update the version in pre-commit. Apparently it also has a problem.