fix(bezier-tokens): fix invalid letter spacing token values (#1821)

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## Self Checklist

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## Summary
<!-- Please brief explanation of the changes made -->

letter spacing 관련 토큰 값이 잘못 변환되던 문제를 수정합니다.

## Details
<!-- Please elaborate description of the changes -->

기존 `extractNumber` 정규식이 숫자만 매칭했기 때문에, 소숫점이 포함된 letter spacing 토큰이 소숫점을
무시한채로 필터링되었습니다.
예컨대 `0.1` 이 `01` 로 필터링이 되면서, parseFloat에 의해 `1` 로 변환이 되었고 결과적으로 10배 높은
값으로 변환되었습니다.

올바르게 동작할 수 있도록 정규식을 개선합니다. 이제 부호와 소숫점 모두 포함하여 필터링할 수 있게 됩니다. 

### Breaking change? (Yes/No)
<!-- If Yes, please describe the impact and migration path for users -->

No

## References
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aware of -->

<img width="795" alt="image"
src="https://github.com/channel-io/bezier-react/assets/58209009/fe99b93c-77aa-4073-b4eb-46d7068b9a9d">

Author: sungik-choi

.changeset/purple-dodos-move.md

@@ -0,0 +1,5 @@
+---
+"@channel.io/bezier-tokens": minor
+---
+
+Fix invalid letter spacing token values

packages/bezier-tokens/scripts/lib/transform.ts

@@ -18,14 +18,7 @@ export const CSSTransforms = {
     transitive: true,
     matcher: (token) =>
       token.attributes?.category === 'font' && token.type === 'dimension',
-    transformer: ({ value }: { value: string }, options) => {
-      const extractedNumber = extractNumber(value)
-      const isNegative = value.trim().startsWith('-')
-      const numberValue =
-        parseFloat(extractedNumber ?? '') /
-        ((options && options.basePxFontSize) || 16)
-      return `${isNegative ? -numberValue : numberValue}rem`
-    },
+    transformer: ({ value }: { value: string }, options) => `${parseFloat(extractNumber(value) ?? '') / ((options && options.basePxFontSize) || 16)}rem`,
   },
   fontFamily: {
     name: 'custom/css/font/family',

packages/bezier-tokens/scripts/lib/utils.ts

@@ -1,6 +1,6 @@
 export const toCamelCase = (str: string) =>
   str.toLowerCase().replace(/[^a-zA-Z0-9]+(.)/g, (_, char) => char.toUpperCase())
 
-export const extractNumber = (str: string) => str.match(/\d+/g)?.join('')
+export const extractNumber = (str: string) => str.match(/-?\d+(\.\d+)?/g)?.join('')
 
 export const toCSSDimension = (value: string) => (/^0[a-zA-Z]+$/.test(value) ? 0 : value)