rename args: is_multiclass -> multiclass

[Borda]

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• Did you write any new necessary tests?

What does this PR do?

fix unclear argument...

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[codecov]

Codecov Report

Merging #162 (c089503) into master (92ea4d7) will decrease coverage by 0.88%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master     #162      +/-   ##
==========================================
- Coverage   96.87%   95.99%   -0.89%     
==========================================
  Files         168       84      -84     
  Lines        5058     2571    -2487     
==========================================
- Hits         4900     2468    -2432     
+ Misses        158      103      -55     

Flag	Coverage Δ
Linux	78.76% <54.16%> (-0.60%)	⬇️
Windows	78.76% <54.16%> (-0.60%)	⬇️
cpu	95.99% <66.66%> (-0.89%)	⬇️
gpu	?
macOS	95.99% <66.66%> (-0.89%)	⬇️
pytest	95.99% <66.66%> (-0.89%)	⬇️
python3.6	95.98% <66.66%> (-0.89%)	⬇️
python3.8	95.99% <66.66%> (-0.89%)	⬇️
python3.9	95.99% <66.66%> (-0.89%)	⬇️
torch1.3.1	94.85% <66.66%> (-0.87%)	⬇️
torch1.4.0	94.98% <66.66%> (-0.87%)	⬇️
torch1.8.1	95.99% <66.66%> (-0.89%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...rics/functional/classification/precision_recall.py	90.47% <40.00%> (-9.53%)	⬇️
torchmetrics/classification/f_beta.py	84.61% <42.85%> (-15.39%)	⬇️
torchmetrics/classification/precision_recall.py	87.50% <42.85%> (-12.50%)	⬇️
...chmetrics/functional/classification/stat_scores.py	93.84% <42.85%> (-6.16%)	⬇️
torchmetrics/functional/classification/f_beta.py	92.00% <50.00%> (-8.00%)	⬇️
torchmetrics/classification/stat_scores.py	97.59% <60.00%> (-2.41%)	⬇️
torchmetrics/utilities/checks.py	92.77% <100.00%> (ø)
__w/1/s/torchmetrics/info.py
__w/1/s/torchmetrics/collections.py
...etrics/functional/regression/explained_variance.py
... and 81 more

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[justusschock]

The or is fine, but why do we want to deal with that topic again? Thought we already settled this?

[Borda]

why do we want to deal with that topic again

what do you mean?

[SkafteNicki]

what about backwards compatibility?

[Borda]

@SkafteNicki mind re-check :]