add missing variable (#17162)

Without the INSTALL_PYTHON_WHEELS=SONIC_UTILITIES_PY3, slave container won't have needed sonic utilities related packages.

Author: Xichen96

rules/docker-dhcp-server.mk

@@ -15,6 +15,7 @@ $(DOCKER_DHCP_SERVER)_LOAD_DOCKERS = $(DOCKER_CONFIG_ENGINE_BULLSEYE)
 
 $(DOCKER_DHCP_SERVER)_INSTALL_DEBS = $(PYTHON3_SWSSCOMMON)
 $(DOCKER_DHCP_SERVER)_PYTHON_WHEELS += $(SONIC_DHCP_SERVER_PY3)
+$(DOCKER_DHCP_SERVER)_INSTALL_PYTHON_WHEELS = $(SONIC_UTILITIES_PY3)
 
 SONIC_DOCKER_IMAGES += $(DOCKER_DHCP_SERVER)
 SONIC_DOCKER_DBG_IMAGES += $(DOCKER_DHCP_SERVER_DBG)