[fix] fix pyyaml warning

https://github.com/yaml/pyyaml/wiki/PyYAML-yaml.load(input)-Deprecation

src/sakia/constants.py

@@ -6,7 +6,7 @@ MAX_CONFIRMATIONS = 6
 with open(
     os.path.join(os.path.dirname(__file__), "root_servers.yml"), "r", encoding="utf-8"
 ) as stream:
-    ROOT_SERVERS = yaml.load(stream)
+    ROOT_SERVERS = yaml.load(stream, Loader=yaml.FullLoader)
 
 with open(
     os.path.join(os.path.dirname(__file__), "g1_licence.html"), "r", encoding="utf-8"