fix: 🐛 disable df casting, drop '' cols from dupe check

[bastienboutonnet]

Description

As explained in #204 and #205 pandas data types are a little too shaky at the minute so we're going to disable casting. This is a regression to pre 1.0.0 behaviour but it worked and at least Snowflake is doing a good job of casting dtypes.

How has this change been tested?

functionality removed, unit tests passing

Supporting doc, tickets, issues

Closes #205

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities (and 0 Security Hotspots to review)
0 Code Smells

No Coverage information
0.0% Duplication

[codecov]

Codecov Report

Merging #206 into dev/nicolas_jaar will decrease coverage by 0.36%.
The diff coverage is 100.00%.

@@                 Coverage Diff                  @@
##           dev/nicolas_jaar     #206      +/-   ##
====================================================
- Coverage             68.54%   68.17%   -0.37%     
====================================================
  Files                    28       28              
  Lines                  1014      993      -21     
====================================================
- Hits                    695      677      -18     
+ Misses                  319      316       -3     

Flag	Coverage Δ
#unittests	68.17% <100.00%> (-0.37%)	⬇️

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Impacted Files	Coverage Δ
core/adapters/impl.py	29.03% <ø> (-0.66%)	⬇️
setup.py	0.00% <ø> (ø)
core/utils.py	66.10% <100.00%> (-3.35%)	⬇️
tests/test_utils.py	100.00% <100.00%> (ø)

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