chore(deps): update github artifact actions (openedx#2571)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/validate.yml

@@ -17,7 +17,7 @@ jobs:
         node-version-file: '.nvmrc'
     - run: make validate.ci
     - name: Archive code coverage results
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v5
       with:
         name: code-coverage-report
         path: coverage/*.*
@@ -27,7 +27,7 @@ jobs:
     steps:
     - uses: actions/checkout@v5
     - name: Download code coverage results
-      uses: actions/download-artifact@v5
+      uses: actions/download-artifact@v6
       with:
         pattern: code-coverage-report
         path: coverage