Use Go 1.22.1

[AlekSi]

Description

toolchain directive should remove some confusion about what Go version is required. Unfortunately, that's another place where the version should be kept in sync.

See also FerretDB/github-actions#251.

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 59.89%. Comparing base (b2a4839) to head (5b19bb7).

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #4155       +/-   ##
===========================================
- Coverage   74.32%   59.89%   -14.43%     
===========================================
  Files         353      353               
  Lines       22738    22738               
===========================================
- Hits        16899    13619     -3280     
- Misses       4551     7795     +3244     
- Partials     1288     1324       +36     

see 124 files with indirect coverage changes

Flag	Coverage Δ
filter-true	48.33% <ø> (-19.50%)	⬇️
hana-1	?
integration	48.33% <ø> (-19.50%)	⬇️
mongodb-1	4.74% <ø> (ø)
postgresql-1	48.17% <ø> (+0.09%)	⬆️
postgresql-2	?
postgresql-3	?
sqlite-1	?
sqlite-2	?
sqlite-3	?
unit	32.56% <ø> (ø)

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

[rumyantseva]

[chilagrow]

Thanks for this!