rcv.data_models: remove unnecessary fields

[glarrain]

For subclasses of RcvDetalleEntry only one of these fields is necessary, which depends on the specific class.

• emisor_razon_social
• receptor_razon_social

These fields had been made optional in #112 (commit 1f21463).

[codecov-io]

Codecov Report

Merging #116 into develop will increase coverage by 0.67%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop     #116      +/-   ##
===========================================
+ Coverage    77.33%   78.00%   +0.67%     
===========================================
  Files           25       25              
  Lines         1725     1705      -20     
  Branches       286      278       -8     
===========================================
- Hits          1334     1330       -4     
+ Misses         267      255      -12     
+ Partials       124      120       -4     

Impacted Files	Coverage Δ
cl_sii/rcv/data_models.py	53.89% <ø> (+3.89%)	⬆️
cl_sii/rcv/parse_csv.py	78.77% <ø> (ø)

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