fix(modal): update modal style

[tongchuliu]

根据设计师要求 调整弹窗底部按钮间距为8px
https://www.figma.com/file/ZIYRsKMYnXJBastapZCVKt/GrowingIO-Design-System?node-id=0%3A16184

[vercel]

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[codecov]

Codecov Report

Merging #1027 (8ac8028) into master (0e459c2) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master     #1027   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          150       150           
  Lines         4912      4912           
  Branches      1315      1315           
=========================================
  Hits          4912      4912           

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[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[tongchuliu]

设计师已验收