dfr get-week for dataframe

Gets week from date.

Signature

> dfr get-week

Examples

Returns week from a date

> let dt = ('2020-08-04T16:39:18+00:00' | into datetime -z 'UTC');
    let df = ([$dt $dt] | dfr into-df);
    $df | dfr get-week
╭───┬────╮
│ # │ 0  │
├───┼────┤
│ 0 │ 32 │
│ 1 │ 32 │
╰───┴────╯