Migration file for slack notification PR

[RonanMorgan]

Create migration file in sqlalchemy in order to the slack_hook column

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.94%. Comparing base (b247038) to head (9841caf).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #481   +/-   ##
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  Coverage   83.94%   83.94%           
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  Files          39       39           
  Lines        1202     1202           
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  Hits         1009     1009           
  Misses        193      193           

Flag	Coverage Δ
backend	83.25% <ø> (ø)
client	93.67% <ø> (ø)

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[frgfm]

Thanks for the PR!
Quick question: have you tested this does initialize the column with null values when there is already a row?

We need to make sure of this before merging.

[frgfm]

Looks good! Have you tried to run it yourself?