chore(deps): update dependency utf-8-validate to v6

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
utf-8-validate	^5.0.9 -> ^6.0.0

---

Release Notes

websockets/utf-8-validate

v6.0.1

Compare Source

v6.0.0

Compare Source

v5.0.10

Compare Source

---

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.

[oliver-sanders]

Is this dev dependency used?

[MetRonnie]

Added in e993c83#r481447212

When removed I get a build warning when running the unit tests

 WARNING  Compiled with 1 warning
 warning  in ./node_modules/subscriptions-transport-ws/node_modules/ws/lib/validation.js
Module not found: Error: Can't resolve 'utf-8-validate' in '~/github/cylc-ui/node_modules/subscriptions-transport-ws/node_modules/ws/lib'

 WEBPACK  Compiled with 1 warning(s)
Warning in ./node_modules/subscriptions-transport-ws/node_modules/ws/lib/validation.js
  Module not found: 'utf-8-validate' in '~/github/cylc-ui/node_modules/subscriptions-transport-ws/node_modules/ws/lib'

Presumably it can be removed when #1028 is tackled. Or if we are happy to live with the warning, we could remove it now?