Update FlopCounterMode usage in throughput.py

[IvanYashchuk]

mods argument is not needed anymore for FlopCounterMode: https://github.com/pytorch/pytorch/blob/ffe506e85350a505be5698c871d50b2fc614406d/torch/utils/flop_counter.py#L595-L596

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📚 Documentation preview 📚: https://pytorch-lightning--19926.org.readthedocs.build/en/19926/

[lantiga]

Thank you @IvanYashchuk !

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 59%. Comparing base (014cdd8) to head (dd9f85b).
Report is 112 commits behind head on master.

❗ There is a different number of reports uploaded between BASE (014cdd8) and HEAD (dd9f85b). Click for more details.

HEAD has 155 uploads less than BASE

Flag	BASE (014cdd8)	HEAD (dd9f85b)
python3.10	19	9
cpu	66	30
lightning	39	22
pytest	47	26
examples	9	0
app	9	0
python3.8	11	7
lightning_fabric	10	9
python3.11	20	14
tpu	1	0
pytorch2.0	12	4
pytest-full	24	8
pytorch_lightning	10	3
pytorch2.1	6	1
pytorch2.2	3	1
pytorch2.3	3	2
lightning_app	2	0

Additional details and impacted files

@@            Coverage Diff            @@
##           master   #19926     +/-   ##
=========================================
- Coverage      84%      59%    -25%     
=========================================
  Files         426      421      -5     
  Lines       35254    35156     -98     
=========================================
- Hits        29628    20750   -8878     
- Misses       5626    14406   +8780     

[awaelchli]

It looks like this was already optional before, so this LGTM and avoids the warning. Thanks!