Update dependency bufferutil to v4.0.4

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
bufferutil	4.0.3 -> 4.0.4

---

Release Notes

websockets/bufferutil

### [`v4.0.4`](https://togithub.com/websockets/bufferutil/compare/v4.0.3...v4.0.4) [Compare Source](https://togithub.com/websockets/bufferutil/compare/v4.0.3...v4.0.4)

---

Configuration

📅 Schedule: 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 WhiteSource Renovate. View repository job log here.

[codecov[bot]]

Codecov Report

Merging #496 (56cd764) into master (d00682f) will not change coverage. The diff coverage is n/a.

@@            Coverage Diff            @@
##            master      #496   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            8         8           
  Lines          342       342           
  Branches        51        51           
=========================================
  Hits           342       342           

Flag	Coverage Δ
unittests	100.00% <ø> (ø)

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

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update d00682f...56cd764. Read the comment docs.