Changes SpinBox for a TextField

[Voldivh]

🦟 Bug fix

Fixes #542

Summary

Changes the implementation of GzSpinBox from a SpinBox to a TextField for MacOS.

Checklist

• [ ] Signed all commits for DCO
• [ ] Added tests
• [ ] Updated documentation (as needed)
• [ ] Updated migration guide (as needed)
• [ ] Consider updating Python bindings (if the library has them)
• [ ] codecheck passed (See contributing)
• [ ] All tests passed (See test coverage)
• [ ] While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[codecov[bot]]

Codecov Report

Merging #572 (dd9080e) into gz-gui8 (b3ed6bd) will not change coverage. The diff coverage is n/a.

:exclamation: Current head dd9080e differs from pull request most recent head f8332f8. Consider uploading reports for the commit f8332f8 to get more accurate results

@@           Coverage Diff            @@
##           gz-gui8     #572   +/-   ##
========================================
  Coverage    68.07%   68.07%           
========================================
  Files           38       38           
  Lines         5369     5369           
========================================
  Hits          3655     3655           
  Misses        1714     1714           

[azeey]

Closing since https://github.com/gazebosim/gz-gui/issues/542 is no longer an issue.