upgrade mysql; bump go version to 1.20

[muir]

This bumps the minimum go version to 1.20 so that the mysql driver can be upgraded

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.70%. Comparing base (4d6362e) to head (7136741).
Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #139      +/-   ##
==========================================
+ Coverage   73.83%   83.70%   +9.87%     
==========================================
  Files          12       12              
  Lines        1261     1080     -181     
==========================================
- Hits          931      904      -27     
+ Misses        267      102     -165     
- Partials       63       74      +11     

Flag	Coverage Δ
go_tests	9.25% <ø> (+0.13%)	⬆️
mysql_tests	51.66% <ø> (+1.62%)	⬆️
pg_tests	52.89% <ø> (+1.68%)	⬆️
singlestore_tests	47.03% <ø> (?)

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