What does this PR do?

fixes Box round prop not respecting responsive

Where should the reviewer start?

styles.js

What testing has been done on this PR?

locally

How should this be manually tested?

    <Box pad="medium" gap="small">
      <Box pad="large" border="all" round="large">
        <Heading>Responsive Box</Heading>
      </Box>

      <Box responsive={false} pad="large" border="all" round="large">
        <Heading>Non-Responsive Box</Heading>
        <Paragraph>round with string prop ❌</Paragraph>
      </Box>

      <Box
        responsive={false}
        pad="large"
        border="all"
        round={{ corner: "top", size: "large" }}
      >
        <Heading>Non-Responsive Box</Heading>
        <Paragraph>round with object prop ✅</Paragraph>
      </Box>
    </Box>

Do Jest tests follow these best practices?

• screen is used for querying.
• The correct query is used. (Refer to this list of queries)
• asFragment() is used for snapshot testing.

Any background context you want to provide?

see issue #6445

For Skeleton there was ${(props) => props.round && roundStyle(props.round, props.responsive, props.theme)}
however there is no responsive prop on Skeleton so just changed to true

What are the relevant issues?

closes #6445

Screenshots (if appropriate)

Do the grommet docs need to be updated?

no

Should this PR be mentioned in the release notes?

yes

Is this change backwards compatible or is it a breaking change?

backwards compatible