Use index as key for weekdays
Use index as key for weekdays

The luxon utils return single-character weekdays, which gives us duplicate keys
T and S.

dmtrKovalenko/material-ui-pickers,callemall/material-ui,callemall/material-ui,mui-org/material-ui,mui-org/material-ui,oliviertassinari/material-ui,callemall/material-ui,rscnt/material-ui,mbrookes/material-ui,oliviertassinari/material-ui,callemall/material-ui,mbrookes/material-ui,mui-org/material-ui,oliviertassinari/material-ui,rscnt/material-ui,rscnt/material-ui,mbrookes/material-ui,dmtrKovalenko/material-ui-pickers