fix(markdown): remove unnecessary spaces

[tmlmt]

Removes unnecessary line break after [compared changes] and unnecessary leading double space before each commit item.
Prettier keeps reformatting it this way after I generate the changelog via --bump

Before:

## v0.4.1

[compare changes](https://github.com/unjs/changelogen/compare/v0.4.0...v0.4.1)


### 🩹 Fixes

  - Bump by patch by default ([7e38438](https://github.com/unjs/changelogen/commit/7e38438))

After:

## v0.4.1

[compare changes](https://github.com/unjs/changelogen/compare/v0.4.0...v0.4.1)

### 🩹 Fixes

- Bump by patch by default ([7e38438](https://github.com/unjs/changelogen/commit/7e38438))

Notes:

• the current test fixture already displays this "clean" formatting: https://github.com/unjs/changelogen/blob/main/test/fixtures/CHANGELOG.md
• I'd be happy to update my other PR feat!: add option to customize types/scopes to exclude #103 if you go ahead with this one. Or the other way around.

[pi0]

Thanks 💯

[tmlmt]

Hey @pi0 do you think you could release v0.5.4 to incorporate that latest merged PR? Thanks !