Add new data entities to dataclass model

[klaasnicolaas]

• Update the data model
• Add new exception
• Add extra pytest tests

[codecov-commenter]

Codecov Report

Merging #16 (0d4a5f7) into master (0e3473e) will increase coverage by 5.70%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #16      +/-   ##
==========================================
+ Coverage   81.39%   87.09%   +5.70%     
==========================================
  Files           4        4              
  Lines          86       93       +7     
  Branches       10       10              
==========================================
+ Hits           70       81      +11     
+ Misses         13        9       -4     
  Partials        3        3              

Impacted Files	Coverage Δ
omnikinverter/__init__.py	100.00% <100.00%> (ø)
omnikinverter/exceptions.py	100.00% <100.00%> (ø)
omnikinverter/models.py	100.00% <100.00%> (+6.66%)	⬆️
omnikinverter/omnikinverter.py	76.47% <0.00%> (+3.92%)	⬆️

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