[Accessibility] "Ensure elements with ARIA role that require child roles contain them

Check that this is really a bug

• I confirm

Reproduction link

https://jquense.github.io/react-big-calendar/examples/index.html?path=/story/about-big-calendar--page

Bug description

when we are having a show more button..

Issue - div[role="row"] is having button[tabindex]

Possible fix - We need to add role="cell" to the parent div of the "Show more" button

Expected Behavior

No Accessibility issue should be found

Actual Behavior

Accessibility issue is observed.

react-big-calendar version

1.11.1

React version

Recat v16.8

Platform/Target and Browser Versions

Edge

Validations

• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.
• Make sure this is a react-big-calendar issue and not an implementation issue

Would you like to open a PR for this bug?

• I'm willing to open a PR