add multiline single quotes for dump a string

[1letter]

this fix issues with custom regex in meta.toml see #229
@gforcada ca you review this PR please?

[gforcada]

🤔 according to the TOML specification a triple quoted single strings is a literal string, i.e. a string that is not parsed at all, which fixes your regex problem.

Testing it on some repositories, I see that it changes ALL triple double quoted strings to triple single quoted strings, which I'm not sure is what we really want...

Looking at https://github.com/zopefoundation/meta I see that since some time ago (see this PR) they switched to tomlkit and that allowed them to remove the custom parser that you are now trying to fix.

As a test I did:

• clone zopefoundation/meta
• create a virutalenv and install config/requirements.txt on it
• clone a random pure python package (in my case zope.authentication)
  • update its .meta.toml configuration with

[tox]
use-flake8 = true
coverage-additional = [
    "coverage: /TOTAL.\\* \\*\\*(\\d+)\\%\\*\\*/",
]

• finally run python config-package.py zope.authentication

The configuration line lands on tox.ini like this:

coverage: /TOTAL.\* \*\*(\d+)\%\*\*/

I would say that this is what you are missing, right? 🍀

I can try to port the PR zopefoundation/meta#215 if you are not faster than me 👍🏾

[1letter]

i will make a new PR with the tomlkit port