refactor(service): add return typing to DNSrecord conversion and comments

selfprivacy_api/graphql/common_types/dns.py

@@ -2,6 +2,7 @@ import typing
 import strawberry
 
 
+# TODO: use https://strawberry.rocks/docs/integrations/pydantic when it is stable
 @strawberry.type
 class DnsRecord:
     """DNS record"""

selfprivacy_api/graphql/common_types/service.py

@@ -89,9 +89,10 @@ def get_storage_usage(root: "Service") -> ServiceStorageUsage:
     )
 
 
-def service_dns_to_graphql(record: ServiceDnsRecord):
-    # Do we really need 2 types for this?
-    # ServiceDNSRecord and DnsRecord are almost identical
+# TODO: This won't be needed when deriving DnsRecord via strawberry pydantic integration
+# https://strawberry.rocks/docs/integrations/pydantic
+# Remove when the link above says it got stable.
+def service_dns_to_graphql(record: ServiceDnsRecord) -> DnsRecord:
     return DnsRecord(
         record_type=record.type,
         name=record.name,