Resolve "Add withdraw_methods and withdraw_addresses to kraken.spot.Funding"

[btschwertfeger]

This PR is adding the new endpoints withdraw_methods and withdraw_addresses to the kraken.spot.Funding client.

[codecov]

Codecov Report

Merging #175 (3a589ae) into master (93cd118) will decrease coverage by 1.69%.
The diff coverage is 56.52%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #175      +/-   ##
==========================================
- Coverage   90.40%   88.72%   -1.69%     
==========================================
  Files          21       21              
  Lines        1845     1871      +26     
==========================================
- Hits         1668     1660       -8     
- Misses        177      211      +34     

Flag	Coverage Δ
unittests	88.72% <56.52%> (-1.69%)	⬇️

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Files	Coverage Δ
kraken/base_api/__init__.py	89.65% <100.00%> (-0.30%)	⬇️
kraken/futures/trade.py	96.20% <100.00%> (ø)
kraken/futures/user.py	66.66% <100.00%> (-19.70%)	⬇️
kraken/spot/__init__.py	100.00% <ø> (ø)
kraken/spot/trade.py	94.33% <100.00%> (ø)
kraken/spot/user.py	99.12% <100.00%> (ø)
kraken/spot/websocket_v1.py	97.16% <100.00%> (ø)
kraken/spot/funding.py	50.74% <9.09%> (-20.37%)	⬇️