Update golang Docker tag to v1.21.4

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
golang	final	patch	1.21.3 -> 1.21.4

---

Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• If you want to rebase/retry this PR, check this box

---

This PR has been generated by Mend Renovate. View repository job log here.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (8b28be7) 66.05% compared to head (87c27a5) 66.05%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #264   +/-   ##
=======================================
  Coverage   66.05%   66.05%           
=======================================
  Files           4        4           
  Lines         436      436           
=======================================
  Hits          288      288           
  Misses        140      140           
  Partials        8        8           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.