test(ci): enforce fmt. of *.{md,js,html,yml} with prettier 3.3.3

This actually may enforce the format of other files than these, but it's
unlikely.

.github/workflows/ci.yml

@@ -619,6 +619,12 @@ jobs:
           cargo fmt -- --check
           cargo fmt --manifest-path xtask/Cargo.toml -- --check
 
+      - name: "Format `**/*.{md,js,html,yml}` files"
+        uses: creyD/[email protected]
+        with:
+          prettier_version: 3.3.3
+          prettier_options: --write .
+
       - name: Check for typos
         uses: crate-ci/[email protected]