Encode str in UnresolvedCustomeType in order to handle unicode names.

[Thalmann]

[Thalmann]

We need this fix in production / we are using it in production.. When do you have time to review?

[codecov[bot]]

Codecov Report

Merging #572 into master will decrease coverage by 0.2%. The diff coverage is 70%.

@@            Coverage Diff            @@
##           master    #572      +/-   ##
=========================================
- Coverage    89.1%   88.9%   -0.21%     
=========================================
  Files          63      63              
  Lines        4683    4703      +20     
  Branches      814     819       +5     
=========================================
+ Hits         4173    4181       +8     
- Misses        330     336       +6     
- Partials      180     186       +6

Impacted Files	Coverage Δ
src/zeep/wsdl/bindings/soap.py	83.24% <100%> (-0.91%)	:arrow_down:
src/zeep/xsd/types/unresolved.py	83.33% <100%> (ø)	:arrow_up:
src/zeep/plugins.py	51.21% <57.14%> (+1.21%)	:arrow_up:
src/zeep/asyncio/__init__.py	0% <0%> (-100%)	:arrow_down:
src/zeep/wsdl/wsdl.py	90.37% <0%> (-5.81%)	:arrow_down:
src/zeep/cache.py	78.3% <0%> (-4.4%)	:arrow_down:
src/zeep/client.py	80.48% <0%> (-4.32%)	:arrow_down:
src/zeep/xsd/types/any.py	73.68% <0%> (-1.32%)	:arrow_down:
src/zeep/wsdl/definitions.py	79.28% <0%> (-1.15%)	:arrow_down:
... and 21 more