Added data-fns module

[anniebock]

1. Added date-fns in package.json

added this line: "date-fns": "^2.27.0", under "dependencies"

2. npm i

[anniebock]

@Jnnybrrn @eych Just wanted to confirm if this is the correct way to add a new module in the repo.

[Jnnybrrn]

Adding the dependency and running npm i is good - but we need to add node_modules/ to the git ignore file.

This PR has loaded all source code for this new module (and it's dependencies) into our git repo which is not what we want