fix: racy random string generation

[alnr]

An obsolete dependency had an illegal concurrent use of "math/rand".Source: https://github.com/gobuffalo/x/blob/913e47c59ca77a753fc68c0daa04b8924b67d7ad/randx/string.go#L17

Removed in favor of a UUID.

[codecov]

Codecov Report

Merging #3555 (9f916dc) into master (116c1e8) will decrease coverage by 0.03%.
The diff coverage is 100.00%.

❗ Current head 9f916dc differs from pull request most recent head 5185c6c. Consider uploading reports for the commit 5185c6c to get more accurate results

@@            Coverage Diff             @@
##           master    #3555      +/-   ##
==========================================
- Coverage   76.64%   76.62%   -0.03%     
==========================================
  Files         129      129              
  Lines        9630     9630              
==========================================
- Hits         7381     7379       -2     
- Misses       1748     1749       +1     
- Partials      501      502       +1     

Impacted Files	Coverage Δ
persistence/sql/persister.go	85.00% <100.00%> (ø)

... and 1 file with indirect coverage changes