Add PI-FGSM and PI-FGSM++ attack and bug fix

[rikonaka]

PR Type and Checklist

What kind of change does this PR introduce?

• [x] ADD ATTACK
  • [x] Add PI-FGSM attack as issues suggested https://github.com/Harry24k/adversarial-attacks-pytorch/issues/143.
  • [x] Add PI-FGSM++ attack as issues suggested https://github.com/Harry24k/adversarial-attacks-pytorch/issues/146.
• [x] Other... Please describe:
  • [x] Fix default value in attack info.
  • [x] Adjust the recommended installation method to install from source.
  • [x] When handling the quantized model https://github.com/Harry24k/adversarial-attacks-pytorch/issues/150, the device initialization code of the Attack class would report an error, so I modified the device initialization process by adding a new device parameter to the __init__ function to manually initialize the device.
  • [x] Fix autotest bug, use pip instead of conda in test, simplify test code.

[codecov-commenter]

Codecov Report

Merging #144 (698a280) into master (c4da6a9) will increase coverage by 0.78%. The diff coverage is 95.10%.

:exclamation: Your organization is not using the GitHub App Integration. As a result you may experience degraded service beginning May 15th. Please install the Github App Integration for your organization. Read more.

@@            Coverage Diff             @@
##           master     #144      +/-   ##
==========================================
+ Coverage   72.63%   73.41%   +0.78%     
==========================================
  Files          42       44       +2     
  Lines        3691     3837     +146     
  Branches      522      582      +60     
==========================================
+ Hits         2681     2817     +136     
- Misses        856      860       +4     
- Partials      154      160       +6     

Impacted Files	Coverage Δ
torchattacks/attack.py	40.43% <72.22%> (-0.45%)	:arrow_down:
code_coverage/test_atks.py	93.10% <94.44%> (+0.12%)	:arrow_up:
torchattacks/attacks/pifgsm.py	95.00% <95.00%> (ø)
torchattacks/attacks/pifgsmplusplus.py	96.00% <96.00%> (ø)
torchattacks/__init__.py	100.00% <100.00%> (ø)
torchattacks/attacks/apgd.py	74.85% <100.00%> (ø)
torchattacks/attacks/apgdt.py	83.97% <100.00%> (ø)
torchattacks/attacks/autoattack.py	80.64% <100.00%> (ø)
torchattacks/attacks/bim.py	93.75% <100.00%> (ø)
torchattacks/attacks/cw.py	100.00% <100.00%> (ø)
... and 31 more

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update c4da6a9...698a280. Read the comment docs.