Fix buy and multi buy

[dwighthalpert]

Since Dec 2nd, IQOption changed some parameters for their buy request, this pull should fix that.

[codecov-io]

Codecov Report

Merging #178 into master will decrease coverage by 0.04%.
The diff coverage is 64.7%.

@@            Coverage Diff             @@
##           master     #178      +/-   ##
==========================================
- Coverage   59.33%   59.28%   -0.05%     
==========================================
  Files          59       59              
  Lines        2090     2056      -34     
==========================================
- Hits         1240     1219      -21     
+ Misses        850      837      -13

Impacted Files	Coverage Δ
iqoptionapi/ws/chanels/subscribe.py	54.54% <ø> (-0.72%)	⬇️
iqoptionapi/api.py	84.88% <ø> (+0.39%)	⬆️
iqoptionapi/ws/chanels/unsubscribe.py	54.54% <ø> (-0.72%)	⬇️
setup.py	0% <ø> (ø)	⬆️
iqoptionapi/ws/chanels/buyv3.py	57.14% <0%> (-2.86%)	⬇️
iqoptionapi/ws/chanels/base.py	100% <100%> (ø)	⬆️
iqoptionapi/stable_api.py	40.13% <100%> (ø)	⬆️
iqoptionapi/ws/client.py	60.3% <66.66%> (+0.4%)	⬆️
iqoptionapi/ws/chanels/buyv2.py	90.9% <80%> (-2.85%)	⬇️
iqoptionapi/expiration.py	51.85% <0%> (-1.86%)	⬇️
... and 4 more

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