add tests for append_to_last_row

[RavSinghChandan]

append_to_last_row in util/misc.py didn't have any tests, so added a few to tests/util/test_misc.py.

it's used to tack extra columns onto the last row of a results csv, and the behaviour that's easy to break in a refactor is the guard: it only writes when there's a header plus at least one data row, otherwise it no-ops and returns False. so the tests cover:

• appending one value to the last data row
• appending multiple values
• header-only file -> returns False, file untouched
• empty file -> returns False, file untouched

ruff check + format are clean.

[tomaarsen]

Hello!

I think this is pretty low priority, but it doesn't really hurt. I merged the tests into one parametrize, as they were all very very similar.

• Tom Aarsen

[tomaarsen]

The test failures seem to be related to torch 2.13 + Windows + BF16 on CPU. I suspect they're missing/not importing a required CPU instruction. I'll leave it be for now.

• Tom Aarsen