Change @shikijs/transformers range by + 1

[richardgill]

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Describe the bug

// [!code highlight:2]
console.log('highlighted')
console.log('not highlighted')

Ranges on transformations include the current line, to me this was very uninuitive.

Instead it could be:

// [!code highlight:2]
console.log('highlighted')
console.log('highlighted')

Currently: // [!code highlight] is effectively // [!code highlight:1]
Becomes: // [!code highlight:0]

I guess this is a breaking change, and it is slightly arbitary - so no worries if you disagree :)

Reproduction

Included in comment

Contributes

• I am willing to submit a PR to fix this issue
• I am willing to submit a PR with failing tests