Adding transactions merely by date creates double entries

[tobiasvielmetter]

Hi, thanks for this great plugin, it helps me streamlining my bookkeeping process.
Yet it seems like transactions are added checking the date only (basically adding all transactions that have been added after the date of the last transaction). This technically seems like a solid approach, but it looks like the date changes on transactions every now and then by a day or two.

My guess is that this issue happens with all payments that take a couple of days to resolve, such as SEPA payments. It does mostly happen with SEPA payments for me.

I am assuming that comparing the reference of a transaction endToEndReference = value["source"] with existing transactions references would circumvent this issue. Looking at the script I was not able to create a workable PR as I am not familiar with the syntax etc, but wanted to point out the issue nevertheless.

Possibly it would be enough to check for if value["status"] == "available" before adding a transaction (status can be either available or pending, assuming the date can still change if the object lists as pending https://stripe.com/docs/api/balance_transactions/list).

See screenshot for an rather extreme example of double entries. Often it's just two entries (payment and fee).