Update version of upload-artifact from v2 to v4

Author: chosak

.github/workflows/test.yml

@@ -57,10 +57,11 @@ jobs:
           TOXENV: python${{ matrix.python }}-django${{ matrix.django }}-wagtail${{ matrix.wagtail }}
 
       - name: Store test coverage
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
-          name: coverage
+          name: coverage-py${{ matrix.python }}-dj${{ matrix.django }}-wag${{ matrix.wagtail }}
           path: .coverage.*
+          include-hidden-files: true
 
   coverage:
     name: coverage
@@ -82,10 +83,12 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install tox
+
       - name: Retrieve test coverage
-        uses: actions/download-artifact@v2
+        uses: actions/download-artifact@v4
         with:
-          name: coverage
+          pattern: coverage-*
+          merge-multiple: true
 
       - name: Check coverage
         run: tox -e coverage