fix: color style issue of code block in post content snapshot page

[ruibaby]

What type of PR is this?

/area ui
/kind bug
/milestone 2.16.x

What this PR does / why we need it:

修复在文章版本历史内容预览中代码块颜色显示异常的问题。

Which issue(s) this PR fixes:

Fixes #5845

Does this PR introduce a user-facing change?

修复在文章版本历史内容预览中代码块颜色显示异常的问题。

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[JohnNiang]

/lgtm

[f2c-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JohnNiang

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Needs approval from an approver in each of these files:

• ui/OWNERS [JohnNiang]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 56.68%. Comparing base (5fdf6c0) to head (607646d).
Report is 200 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #5982      +/-   ##
============================================
- Coverage     56.91%   56.68%   -0.23%     
- Complexity     3319     3475     +156     
============================================
  Files           587      609      +22     
  Lines         18968    20478    +1510     
  Branches       1401     1418      +17     
============================================
+ Hits          10795    11608     +813     
- Misses         7594     8292     +698     
+ Partials        579      578       -1     

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