test: add simple Sequelize tests

[olavloite]

Adds some simple tests to verify that Sequelize works.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.97%. Comparing base (9a6ba6a) to head (2865401).
Report is 300 commits behind head on postgresql-dialect.

❗ Current head 2865401 differs from pull request most recent head bf20c62. Consider uploading reports for the commit bf20c62 to get more accurate results

Additional details and impacted files

@@                   Coverage Diff                    @@
##             postgresql-dialect    #1172      +/-   ##
========================================================
+ Coverage                 90.86%   90.97%   +0.10%     
- Complexity                 2656     2685      +29     
========================================================
  Files                       141      143       +2     
  Lines                      9054     9162     +108     
  Branches                   1319     1337      +18     
========================================================
+ Hits                       8227     8335     +108     
  Misses                      555      555              
  Partials                    272      272              

Flag	Coverage Δ
all_tests	90.97% <ø> (+0.10%)	⬆️

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