Add StrEnum for device_tracker SourceType (#75892)

Add StrEnum for device_tracker SourceType

homeassistant/components/device_tracker/const.py

@@ -1,8 +1,12 @@
 """Device tracker constants."""
+from __future__ import annotations
+
 from datetime import timedelta
 import logging
 from typing import Final
 
+from homeassistant.backports.enum import StrEnum
+
 LOGGER: Final = logging.getLogger(__package__)
 
 DOMAIN: Final = "device_tracker"
@@ -11,11 +15,23 @@ ENTITY_ID_FORMAT: Final = DOMAIN + ".{}"
 PLATFORM_TYPE_LEGACY: Final = "legacy"
 PLATFORM_TYPE_ENTITY: Final = "entity_platform"
 
+# SOURCE_TYPE_* below are deprecated as of 2022.9
+# use the SourceType enum instead.
 SOURCE_TYPE_GPS: Final = "gps"
 SOURCE_TYPE_ROUTER: Final = "router"
 SOURCE_TYPE_BLUETOOTH: Final = "bluetooth"
 SOURCE_TYPE_BLUETOOTH_LE: Final = "bluetooth_le"
 
+
+class SourceType(StrEnum):
+    """Source type for device trackers."""
+
+    GPS = "gps"
+    ROUTER = "router"
+    BLUETOOTH = "bluetooth"
+    BLUETOOTH_LE = "bluetooth_le"
+
+
 CONF_SCAN_INTERVAL: Final = "interval_seconds"
 SCAN_INTERVAL: Final = timedelta(seconds=12)