🐛 Bug Report

Documents instructs us to set Table theme to null, if we dont want one. But TS file doesnt allow it.

From docs:

Lib version: 4.4.0

Steps To Reproduce

Example from Docs, with style.theme set to null
// add a table to a sheet

ws.addTable({
  name: 'MyTable',
  ref: 'A1',
  headerRow: true,
  totalsRow: true,
  style: {
    theme: null,
    showRowStripes: true,
  },
  columns: [
    {name: 'Date', totalsRowLabel: 'Totals:', filterButton: true},
    {name: 'Amount', totalsRowFunction: 'sum', filterButton: false},
  ],
  rows: [
    [new Date('2019-07-20'), 70.10],
    [new Date('2019-07-21'), 70.60],
    [new Date('2019-07-22'), 70.10],
  ],
});

The expected behaviour:

yarn build runs.

but I get a failed build, stating that null is not accepted.
these are the types:
https://github.com/exceljs/exceljs/blob/master/index.d.ts#L1788

Possible solution (optional, but very helpful):

I think the best solution, is to add null to the linked type. Since it runs fine, just doesnt build.