Add missing check_health argument to Connection overrides (#1323)

Now matches the parent class signature. Running the benchmark previously
failed with the error:

    TypeError: send_packed_command() got an unexpected keyword argument 'check_health'

benchmarks/command_packer_benchmark.py

@@ -7,7 +7,7 @@
 
 
 class StringJoiningConnection(Connection):
-    def send_packed_command(self, command):
+    def send_packed_command(self, command, check_health=True):
         "Send an already packed command to the Redis server"
         if not self._sock:
             self.connect()
@@ -38,7 +38,7 @@ def pack_command(self, *args):
 
 
 class ListJoiningConnection(Connection):
-    def send_packed_command(self, command):
+    def send_packed_command(self, command, check_health=True):
         if not self._sock:
             self.connect()
         try: