Revert "Update react monorepo to v17 (#1913)" to fix Gatsby
Created by: sqs
This reverts commit b807166e3e1853f4bf10dbe332d12c9049fb0382.
React 17 breaks Gatsby: https://github.com/gatsbyjs/gatsby/issues/27592
Created by: sqs
This reverts commit b807166e3e1853f4bf10dbe332d12c9049fb0382.
React 17 breaks Gatsby: https://github.com/gatsbyjs/gatsby/issues/27592