Add max-width for the post publish panel buttons.

[juanfra]

Description

Adding max-width for the new post publish panel buttons distribution for the break-mobile() breakpoint. Applying @MichaelArestad's suggestion here.

How has this been tested?

Checked the new styles at different screen sizes.

Screenshots

Types of changes

• Adding a max-width on an element for a certain viewport.

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR.

[MichaelArestad]

This change looks good to me. Nice work and thanks for following up so quickly.