fix(calendar): Change type on YearButtonLabel to be the type ReactNode.

[KeeganW]

Description

This changes the type of previousYearButtonLabel and nextYearButtonLabel to be React.ReactNode. This mirrors previousMonthButtonLabel and nextMonthButtonLabel, which is already of type React.ReactNode.

Problem
When using month picker, the YearButtonLabels allow for specifying a ReactNode (the code here implies that it is expected to not always be a string), but typescript rightfully complains because the type doesn't line up.

Changes
This PR changes previousYearButtonLabel and nextYearButtonLabel to be the type React.ReactNode instead of string

Screenshots

NA

To reviewers

Contribution checklist

• I have followed the contributing guidelines.
• I have added sufficient test coverage for my changes.
• I have formatted my code with Prettier and checked for linting issues with ESLint for code readability.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.11%. Comparing base (72bd657) to head (69ef33d).
Report is 16 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5659      +/-   ##
==========================================
+ Coverage   96.99%   97.11%   +0.11%     
==========================================
  Files          30       30              
  Lines        3363     3363              
  Branches     1419     1423       +4     
==========================================
+ Hits         3262     3266       +4     
+ Misses         99       95       -4     
  Partials        2        2              

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