Bump actions/download-artifact from 2 to 4.1.7 in /.github/workflows

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 2 to 4.1.7.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v2...v4.1.7)

---
updated-dependencies:
- dependency-name: actions/download-artifact
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/validate.yml

@@ -48,7 +48,7 @@ jobs:
 
     steps:
     - name: Fetch built site
-      uses: actions/download-artifact@v2
+      uses: actions/download-artifact@v4.1.7
       with:
         name: Built site ${{ github.run_number }}
         path: ./_site
@@ -67,7 +67,7 @@ jobs:
 
     steps:
     - name: Fetch built site
-      uses: actions/download-artifact@v2
+      uses: actions/download-artifact@v4.1.7
       with:
         name: Built site ${{ github.run_number }}
         path: ./_site
@@ -99,7 +99,7 @@ jobs:
       - name: Fetch repository for `lighthouserc.json`
         uses: actions/checkout@v2
       - name: Fetch built site
-        uses: actions/download-artifact@v2
+        uses: actions/download-artifact@v4.1.7
         with:
           name: Built site ${{ github.run_number }}
           path: ./_site