Make sure crow vtps reader can handle csv files with duplicate timestamps

[stijnvanhoey]

See aloftdata/vptstools#22, we have to check if this works and take first one when it occurs.

[peterdesmet]

@stijnvanhoey the application works with duplicate timestamps, but I think the last, rather than the first row is used.

[peterdesmet]

Todo:

• Use first row
• Add a test for this

[stijnvanhoey]

I would convert (or add to) the txt-files in the tests to the corresponding CSV version in these tests:

• https://github.com/inbo/crow/blob/main/tests/unit/crow.spec.ts#L98
• https://github.com/inbo/crow/blob/main/tests/unit/crow.spec.ts#L161

This would check the usage of the first occurrence.