Remove specifying suffix and prefix of python module

[jslee02]

They are set by pybind11_add_module().

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[codecov]

Codecov Report

Merging #1378 into master will increase coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1378      +/-   ##
==========================================
+ Coverage   56.95%   56.98%   +0.03%     
==========================================
  Files         366      366              
  Lines       27460    27460              
==========================================
+ Hits        15640    15649       +9     
+ Misses      11820    11811       -9

Impacted Files	Coverage Δ
dart/dynamics/Skeleton.cpp	66.22% <0%> (+0.16%)	⬆️
dart/dynamics/EulerJoint.cpp	73% <0%> (+3.68%)	⬆️