Allow customizing the release_command

Hello

Due to unfortunate side effects of the `gh release edit --daft=false`, we do not want to run this command. That is because it automatically marks the release as latest where we do not want it to do so inside a monorepo with multple packages, including one main package that we'd like to always be marked as latest.

As far as I see, there is no way to [customize this](https://github.com/axodotdev/cargo-dist/blob/5ae4cffc4ecf4f4d26b4d4e6970cad0f63cb0931/cargo-dist/src/backend/ci/github.rs#L516)

So far my only workaround is to manually edit the workflow file and allow it to be dirty, which is not really future proof.

Would you be open to a PR to allow customizing this command ?

Start in cargo-dist/src/backend/ci/github.rs at the release command referenced by the issue, then trace how that command reaches the generated workflow. Identify the existing configuration path and check how manual workflow edits currently affect it. Done means the release command can be customized without leaving the generated workflow dirty and without forcing releases to become latest.

Written by the indexing model from the issue text.