[2.1.6] Budget Flow does not import "0" entries via CSV Import

@Fabian

You asked me to email you to investigate, but your time is better spent improving the app, so I looked into this for hours.

When importing transactions with “0” amount, those entries are not imported. It doesn’t even tell you why! It just says “400 of 432 entries imported. 32 entries skipped”.

I can’t think of a rationale as to why 0 entries shouldn’t be imported.