feat(ci): upgrade to prettier v3

Switch Lint CI check for prettier to latest official stable version v3. Everything fixed via #2669 seems to be included in prettier@3 since quite a while now, so no need to stay at a fixed commit anymore.

.github/workflows/ci.yml

@@ -16,8 +16,8 @@ jobs:
       run: npm run lint
     - name: Assert LESS files formatting using Prettier
       run: >
-        yarn add -D github:prettier/prettier#c6e026ea28
-        && npx prettier --loglevel warn '!dist' '!test/coverage' '!src/semantic.less' '**/*.{css,less,overrides,variables}' --write
+        yarn add -D prettier@^3
+        && npx prettier --log-level warn '!dist' '!test/coverage' '!src/semantic.less' '**/*.{css,less,overrides,variables}' --write
         && git restore package.json yarn.lock
         && git add . -N && git diff --color --exit-code
   test: