feat(gsheets2): retrieve unformatted values instead of formatted ones

[testinnplayin]

Change Summary

By default google sheets applies the decimal separator defined in the gsheet locale.
We want values such as "," to be correctly interpreted so we added the parameter valueRenderOption=UNFORMATTED_VALUE' to the URL used to retrieve data in the connector

Checklist

• Unit tests for the changes exist
• Tests pass on CI and coverage remains at 100%
• Documentation reflects the changes where applicable

[codecov]

Codecov Report

Merging #214 into master will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #214   +/-   ##
=======================================
  Coverage   97.75%   97.75%           
=======================================
  Files          43       43           
  Lines        2223     2223           
=======================================
  Hits         2173     2173           
  Misses         50       50           

Impacted Files	Coverage Δ
...ctors/google_sheets_2/google_sheets_2_connector.py	100.00% <100.00%> (ø)

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[raphaelvignes]

We created a new PR based on (#210) to integrate changes from Rachelle PR