github-actions: upgrade upload-artifact and download-artifact

Author: cyrilst

.github/workflows/tests.yml

@@ -32,7 +32,7 @@ jobs:
         run: make get-deps check
 
       - name: Upload coverage artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: coverage-${{ matrix.go }}
           path: test/coverage.out
@@ -46,7 +46,7 @@ jobs:
         uses: actions/checkout@v6
 
       - name: Download coverage artifact
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v8
         with:
           name: coverage-stable