go with v4

Author: connorhu

.github/workflows/tests.yml

@@ -68,7 +68,7 @@ jobs:
       - name: Run test suite
         run: composer test:unit -- --coverage-clover coverage.xml
       - name: Upload coverage file
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: 'phpunit-${{ matrix.php-version }}-${{ matrix.sf-version }}-coverage'
           path: 'coverage.xml'
@@ -125,7 +125,7 @@ jobs:
           fetch-depth: 2
 
       - name: Download coverage files
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           path: reports