Test: improve coverage

[mammothb]

• Improve coverage by testing some edge cases
• Skip branch and code coverage at various places due to "peephole" optimization
  • Ref: continue marked as not covered nedbat/coveragepy#198
• Skip branch and code coverage at unreachable code

[codecov-commenter]

Codecov Report

Merging #105 (43765e0) into master (c09807c) will increase coverage by 1.71%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           master      #105      +/-   ##
===========================================
+ Coverage   98.28%   100.00%   +1.71%     
===========================================
  Files           8         8              
  Lines         818       874      +56     
  Branches      199       236      +37     
===========================================
+ Hits          804       874      +70     
+ Misses          6         0       -6     
+ Partials        8         0       -8     

Impacted Files	Coverage Δ
symspellpy/suggest_item.py	100.00% <ø> (ø)
symspellpy/symspellpy.py	100.00% <100.00%> (+3.38%)	⬆️

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