deps(server): Use pgx v5 for database migration

[hk21702]

pgx v4 has been considered EOL for a while and has known security issues. Here, we migrate the database migration tasks, the last bits of code that still use V4 of the pgx driver, to pgx v5.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.92%. Comparing base (1e2d962) to head (19d9d08).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #334      +/-   ##
==========================================
- Coverage   88.97%   88.92%   -0.06%     
==========================================
  Files          56       56              
  Lines        5317     5317              
==========================================
- Hits         4731     4728       -3     
- Misses        586      589       +3     

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