fix(notifiction): Complement duration missing type definition.

[duhongjun]

First of all, thank you for your contribution! :-)

Please makes sure that these checkboxes are checked before submitting your PR, thank you!

• Make sure that you propose PR to right branch: bugfix for master, feature for latest active branch feature-x.x.
• Make sure that you follow antd's code convention.
• Run npm run lint and fix those errors before submitting in order to keep consistent code style.
• Rebase before creating a PR to keep commit history clear.
• Add some descriptions and refer relative issues for you PR.

Extra checklist:

if isBugFix :

• Make sure that you add at least one unit test for the bug which you had fixed.

elif isNewFeature :

• Update API docs for the component.
• Update/Add demo to demonstrate new feature.
• Update TypeScript definition for the component.
• Add unit tests for the feature.

[duhongjun]

#9109

[codecov]

Codecov Report

Merging #9120 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #9120   +/-   ##
=======================================
  Coverage   85.26%   85.26%           
=======================================
  Files         195      195           
  Lines        4677     4677           
  Branches     1379     1379           
=======================================
  Hits         3988     3988           
  Misses        689      689

Impacted Files	Coverage Δ
components/notification/index.tsx	95.65% <ø> (ø)	⬆️

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[yesmeck]

Thanks!