fix: linter errors

Author: karenc-bq

aws_advanced_python_wrapper/utils/rdsutils.py

@@ -126,7 +126,7 @@ def is_rds_custom_cluster_dns(self, host: str) -> bool:
 
     def is_rds_dns(self, host: str) -> bool:
         if not host or not host.strip():
-            return None
+            return False
 
         pattern = self._find(host, [RdsUtils.AURORA_DNS_PATTERN,
                                     RdsUtils.AURORA_CHINA_DNS_PATTERN,
@@ -235,9 +235,13 @@ def _find(self, host: str, patterns: list):
             match = RdsUtils.CACHE_DNS_PATTERNS.get(host)
             if match:
                 return match
-            else:
-                match = search(pattern, host)
+
+            match = search(pattern, host)
+            if match:
                 RdsUtils.CACHE_DNS_PATTERNS[host] = match
+                return match
+
+        return None
 
     def _get_regex_group(self, pattern: Match[str], group_name: str):
         return pattern.group(group_name)