temporal: Fixed ruff errors in t.list

[arohanajit]

Fixed ruff errors regarding path and context manager

[petrasovaa]

This is probably not the best approach, you are doubling the amount of code, see the approach used in

grass/temporal/t.rast.what/t.rast.what.py

Line 361 in 69a9b89

with open(output, "w") if output != "-" else nullcontext(sys.stdout) as out_file:

[echoix]

Yep, I agree with @petrasovaa here, I worked a bit to find that solution. The nullcontext is the appropriate choice for these situations, where sometimes a context manager is needed, but sometimes not, and you want to keep the "shape" of a context manager in both cases. See #4224