Update the outdated action versions to v4 in workflow files

.github/workflows/build-timestamped-master.yml

@@ -41,7 +41,7 @@ jobs:
       - name: Generate Codecov Report
         uses: codecov/codecov-action@v2
       - name: Upload Artifact
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: ballerina-runtime
           path: target/ballerina-runtime/

.github/workflows/pull-request.yml

@@ -25,7 +25,7 @@ jobs:
           packagePAT: ${{ secrets.GITHUB_TOKEN }}
         run: ./gradlew build --scan
       - name: Archive Code Coverage JSON
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: Code Coverage JSON
           path: stan-ballerina/target/report/test_results.json