fix(config): remove deny_unknown_fields

[lucasfernog]

What kind of change does this PR introduce?

• Bugfix
• Feature
• Docs
• New Binding issue #___
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change?

• Yes, and the changes were approved in issue #___
• No

Checklist

• When resolving issues, they are referenced in the PR's title (e.g fix: remove a typo, closes #___, #___)
• A change file is added if any packages will require a version bump due to this PR per the instructions in the readme.
• I have added a convincing reason for adding this feature, if necessary

Other information

[FabianLars]

what do you think about logging unknown fields in the future (only on values actually specified in the config if possible)?

[lucasfernog]

The CLI validates the schema so we're not left in the dark here. Idk if it can be improved.

[FabianLars]

Yeah, i was thinking about what if users see new features/config options and only update the cli and wonder why the config doesn't have any effect

[lucasfernog]

I don't think there's an easy way to do that using serde. Maybe we should just improve the error message instead.

[lucasfernog]

I think I'll change the CLI to pass only the merge config instead to avoid conflicts.

[lucasfernog]

Closing in favor of #4598