ditch `date-fns`

[maifeeulasad]

As per bundlephobia analysis on to-spreadsheet@1.1.4, we can see that date-fns is taking around 35% of the bundle. And we have only one dependency to date-fns, and that is to generate today's date in specific format. We don't need any other fancy function from this.

So we can ditch it for now.

Snap:

ref: https://bundlephobia.com/package/to-spreadsheet@1.1.4