Bump pgx

[AlekSi]

Description

Fixes a potential security issue.

Also, downgrade vuln to work around its problem.

Readiness checklist

• I added/updated unit tests (and they pass).
• I added/updated integration/compatibility tests (and they pass).
• I added/updated comments and checked rendering.
• I made spot refactorings.
• I updated user documentation.
• I ran task all, and it passed.
• I ensured that PR title is good enough for the changelog.
• (for maintainers only) I set Reviewers (@FerretDB/core), Milestone (Next), Labels, Project and project's Sprint fields.
• I marked all done items in this checklist.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.87%. Comparing base (1bfc549) to head (6403286).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4190      +/-   ##
==========================================
- Coverage   74.96%   73.87%   -1.10%     
==========================================
  Files         339      339              
  Lines       22827    22827              
==========================================
- Hits        17113    16864     -249     
- Misses       4417     4679     +262     
+ Partials     1297     1284      -13     

see 26 files with indirect coverage changes

Flag	Coverage Δ
filter-false	?
filter-true	67.34% <ø> (-1.47%)	⬇️
hana-1	?
integration	67.34% <ø> (-1.51%)	⬇️
mongodb-1	5.13% <ø> (ø)
mysql-1	?
mysql-2	?
mysql-3	?
postgresql-1	46.52% <ø> (-0.11%)	⬇️
postgresql-2	49.51% <ø> (-0.13%)	⬇️
postgresql-3	49.87% <ø> (-0.09%)	⬇️
sqlite-1	45.66% <ø> (-0.08%)	⬇️
sqlite-2	48.66% <ø> (-0.18%)	⬇️
sqlite-3	49.03% <ø> (-0.10%)	⬇️
unit	32.55% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

[chilagrow]

Thank you for this 🤗