fix: import error

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.base import DNSProvider
 from dns_providers import DNSProviderFactory