@scaleway/changesets-renovate Ability to Skip the commit

[wrighbr]

Is your feature request related to a problem? Please describe.
We run a self hosted renovate bot and want to be able to run a "postUpgradeTasks" to create a changeset see below.

{
  "postUpgradeTasks": {
    "commands": [
         "npm i -g @scaleway/changesets-renovate && changesets-renovate",
    ]
  }
}

According to the doco we don't need to commit the modified files https://docs.renovatebot.com/configuration-options/#postupgradetasks

Describe the solution you'd like
I want the ability to be able skip the git commit steps within the changeset-renovate cli this could be either achieved by an environmental variable SKIP_COMMIT=TRUE changesets-renovate or cli changesets-renovate --skip-commit