Added tests for checkbox button

[SaidShah]

• Related GitHub issue(s) linked in PR description
• Destination branch merged, built and tested with your changes
• Code formatted and follows best practices and patterns
• Code builds cleanly (no additional warnings or errors)
• Manually tested
• Automated tests are passing
• No decreases in automated test coverage
• Documentation updated (readme, docs, comments, etc.)
• Localization: No hard-coded error messages in code files (minimally in string constants)
• New component and/ or properties? Make sure to update storybook

Closes #5

[codecov]

Codecov Report

Merging #61 into main will increase coverage by 0.75%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #61      +/-   ##
==========================================
+ Coverage   20.62%   21.38%   +0.75%     
==========================================
  Files          51       51              
  Lines         897      898       +1     
  Branches      209      209              
==========================================
+ Hits          185      192       +7     
+ Misses        702      696       -6     
  Partials       10       10              

Impacted Files	Coverage Δ
src/atoms/forms/checkbox-button.tsx	100.00% <100.00%> (+100.00%)	⬆️

---

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 6d56e16...a0e2ecd. Read the comment docs.

[wintondeshong]

@SaidShah After adding the missing endregion statement should be good to go 👍