Potential fix for code scanning alert no. 19: Unused import

Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

Author: Leechael

custom-domain/dstack-ingress/scripts/certman.py

@@ -10,7 +10,7 @@
 # Add script directory to path to import dns_providers
 sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
 
-from dns_providers.base import DNSProvider
+
 from dns_providers import DNSProviderFactory