style: optimization calendar year content

[xrkffgg]

🤔 This is a ...

• New feature
• Bug fix
• Site / document update
• Component style update
• TypeScript definition update
• Refactoring
• Code style optimization
• Test Case
• Branch merge
• Other (about what?)

🔗 Related issue link

none

💡 Background and solution

• https://next.ant.design/components/calendar-cn/#components-calendar-demo-notice-calendar
• 选择年
• 点击文字
• 可观察到文字颜色为白色，与背景色靠近，无法分辨。
• 故增加 文字颜色设置。

📝 Changelog

Language	Changelog
🇺🇸 English	Add the Calendar component's custom default font color for display content
🇨🇳 Chinese	增加 Calendar 组件 自定义显示内容的默认字体颜色

☑️ Self Check before Merge

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• TypeScript definition is updated/provided or not needed
• Changelog is provided or not needed

[ant-design-bot]

[codesandbox-ci]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

Latest deployment of this branch, based on commit 22500e7:

Sandbox	Source
antd reproduction template	Configuration

[codecov]

Codecov Report

Merging #21598 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #21598   +/-   ##
=======================================
  Coverage   97.86%   97.86%           
=======================================
  Files         304      304           
  Lines        7015     7015           
  Branches     1944     1944           
=======================================
  Hits         6865     6865           
  Misses        150      150

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 50087b2...22500e7. Read the comment docs.