Update *load-artifact action to v4

Author: Philip-Larsen-Donnelly

.github/workflows/dhis2-verify-app.yml

@@ -34,7 +34,7 @@ jobs:
             - name: Build
               run: yarn d2-app-scripts build
 
-            - uses: actions/upload-artifact@v2
+            - uses: actions/upload-artifact@v4
               with:
                   name: app-build
                   path: |
@@ -93,7 +93,7 @@ jobs:
               with:
                   node-version: 14.x
 
-            - uses: actions/download-artifact@v2
+            - uses: actions/download-artifact@v4
               with:
                   name: app-build