chore: upgrade to Vega-Lite v6 and Vega-Embed v7#81

thomasp85 merged 1 commit intoposit-dev:mainposit-dev/ggsql:mainfrom

cpsievert:feature/vegalite-v6-upgradecpsievert/ggsql:feature/vegalite-v6-upgradeCopy head branch name to clipboard