Fix type annotation on extract_registry_entry_config (#3623)

Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>

esphome/cpp_helpers.py

@@ -13,7 +13,7 @@ from esphome.const import (
 
 # pylint: disable=unused-import
 from esphome.core import coroutine, ID, CORE
-from esphome.types import ConfigType
+from esphome.types import ConfigType, ConfigFragmentType
 from esphome.cpp_generator import add, get_variable
 from esphome.cpp_types import App
 from esphome.util import Registry, RegistryEntry
@@ -108,8 +108,9 @@ async def setup_entity(var, config):
 
 
 def extract_registry_entry_config(
-    registry: Registry, full_config: ConfigType
-) -> RegistryEntry:
+    registry: Registry,
+    full_config: ConfigType,
+) -> tuple[RegistryEntry, ConfigFragmentType]:
     key, config = next((k, v) for k, v in full_config.items() if k in registry)
     return registry[key], config