Fix due date type when creating a new item

[riexn]

fixed

item.add()'s due property had the incorrect type for it. Based on the documentation, it should be either:

"due": {"string":  "tomorrow at 12"}
"due": {"string": "tomorrow at 12", "timezone": "Asia/Jakarta"} // timezone doesn't seem to work anymore, since they mentioned it will always be null
"due": {"date": "2018-10-14"}

added

• .env has been added as an ignored file in git for security reasons
• dotenv/crossenv to create a local .env file for local testing
• tests for due date being set as a string or a date

changed

• test file changed to a typescript file to detect any typing issues early on

[lordnox]

Thank you 🙏!

I might have missed this when implementing the types in the first place. I'll take a look later

[romgrk]

@lordnox let us know if anything needs to be changed, but I'll merge as it looks fine to me.