Add support for username/password authentication

Derived from NoneGG/aredis#186

Author: alisaifee

coredis/__init__.py

@@ -3,6 +3,9 @@
 from coredis.connection import ClusterConnection, Connection, UnixDomainSocketConnection
 from coredis.exceptions import (
     AskError,
+    AuthenticationFailureError,
+    AuthenticationRequiredError,
+    AuthorizationError,
     BusyLoadingError,
     CacheError,
     ClusterCrossSlotError,
@@ -41,6 +44,9 @@
     "ConnectionPool",
     "ClusterConnectionPool",
     "AskError",
+    "AuthenticationFailureError",
+    "AuthenticationRequiredError",
+    "AuthorizationError",
     "BusyLoadingError",
     "CacheError",
     "ClusterCrossSlotError",

coredis/client.py

@@ -140,6 +140,7 @@ def __init__(
         host="localhost",
         port=6379,
         db=0,
+        username=None,
         password=None,
         stream_timeout=None,
         connect_timeout=None,
@@ -164,6 +165,7 @@ def __init__(
         if not connection_pool:
             kwargs = {
                 "db": db,
+                "username": username,
                 "password": password,
                 "encoding": encoding,
                 "stream_timeout": stream_timeout,