chore: Upgrade actions/upload-artifact from v3 to v4 in CI workflow for improved artifact handling

Author: omeraplak

.github/workflows/ci.yml

@@ -89,7 +89,7 @@ jobs:
       run: twine check dist/*
 
     - name: Upload build artifacts
-      uses: actions/upload-artifact@v3
+      uses: actions/upload-artifact@v4
       with:
         name: python-package-distributions
         path: dist/
@@ -121,7 +121,7 @@ jobs:
         bandit -r voltagent/ || true
 
     - name: Upload security reports
-      uses: actions/upload-artifact@v3
+      uses: actions/upload-artifact@v4
       if: always()
       with:
         name: security-reports