Rewrite README update script in Python and remove from pre-commit

[jwodder]

• .update-readme-help.sh benefits from being rewritten in Python because:

  • The syntax for sed -i with no extension differs between Linux and macOS, and thus the current shell script is not portable.
  • The Python script is more efficient, as it only needs to pass over the file once, where as the shell script processes the file twice.

• Running .update-readme-help.sh via pre-commit is problematic, as it requires duct to be installed in the current Python environment, yet no provision is made for this. Unless you can come up with a simple, clean way to install duct in editable mode in some virtualenv, I think it's better to just leave this out of pre-commit.

[asmacdo]

Ah thank you, it was clunky and driving me crazy :)

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 86.45%. Comparing base (7d0fd7a) to head (7086b75).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #75 +/- ## ========================================== - Coverage 87.25% 86.45% -0.80% ========================================== Files 1 1 Lines 251 251 Branches 39 39 ========================================== - Hits 219 217 -2 - Misses 24 26 +2 Partials 8 8 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[asmacdo]

CI fail is just code-cov. I tested it out and it worked as expected.