Prune Expired Invoices From Invoice List

[elraphty]

Context

Currently, we save all the invoice payment requests of invoices generated by swarm4 on the invoice_lists table and check to see if the invoice is settled so we can change the status.

Design

We want to delete every expired invoice from the invoice_list table that has not been paid, so when we poll for a workspace's invoices, we check the expiration time of the invoice, if an invoice has expired and the invoice has not been paid we will delete the invoice from the invoice_list table.

Acceptance Criteria

• I've tested on Chrome
• I've created a test that...
• I have rebased and tested locally before submitting my PR
• I can submit a PR within 2 days of taking the bounty

Here is an example backend test