[Test] Add more test cases

[kozistr]

Change Log

• test case for PCGrad
• test cases for the parameters
  • learning_rate
  • weight_decay
  • eps
  • betas

[codecov-commenter]

Codecov Report

Merging #45 (033a842) into main (5f1ef59) will increase coverage by 7.99%.
The diff coverage is 97.29%.

@@            Coverage Diff             @@
##             main      #45      +/-   ##
==========================================
+ Coverage   71.03%   79.02%   +7.99%     
==========================================
  Files          24       24              
  Lines        1602     1626      +24     
==========================================
+ Hits         1138     1285     +147     
+ Misses        464      341     -123     

Impacted Files	Coverage Δ
pytorch_optimizer/radam.py	87.64% <ø> (+5.61%)	⬆️
pytorch_optimizer/pcgrad.py	96.20% <91.66%> (+69.95%)	⬆️
pytorch_optimizer/adabelief.py	73.17% <100.00%> (+2.90%)	⬆️
pytorch_optimizer/adabound.py	81.25% <100.00%> (+12.89%)	⬆️
pytorch_optimizer/ranger21.py	92.00% <100.00%> (+0.58%)	⬆️
pytorch_optimizer/madgrad.py	71.91% <0.00%> (+3.37%)	⬆️
pytorch_optimizer/sgdp.py	95.71% <0.00%> (+4.28%)	⬆️
pytorch_optimizer/diffrgrad.py	92.47% <0.00%> (+5.37%)	⬆️
pytorch_optimizer/adamp.py	93.33% <0.00%> (+5.55%)	⬆️
pytorch_optimizer/ranger.py	94.44% <0.00%> (+5.55%)	⬆️
... and 6 more

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