Migrate to new const data types

[andreasbrett]

As of HA Core 2025.1 following consts will deprecate:

• SOURCE_TYPE_GPS
• LENGTH_KILOMETERS
• LENGTH_METERS
• SPEED_KILOMETERS_PER_HOUR

see HA logs:

2024-03-06 08:19:38.275 WARNING (MainThread) [homeassistant.components.device_tracker] SOURCE_TYPE_GPS was used from biketrax, this is a deprecated constant which will be removed in HA Core 2025.1. Use SourceType.GPS instead, please create a bug report at https://www.github.com/basilfx/homeassistant-biketrax/issues
2024-03-06 08:19:38.348 WARNING (MainThread) [homeassistant.components.device_tracker] SOURCE_TYPE_GPS was used from biketrax, this is a deprecated constant which will be removed in HA Core 2025.1. Use SourceType.GPS instead, please create a bug report at https://www.github.com/basilfx/homeassistant-biketrax/issues
2024-03-06 08:19:38.510 WARNING (MainThread) [homeassistant.const] LENGTH_KILOMETERS was used from biketrax, this is a deprecated constant which will be removed in HA Core 2025.1. Use UnitOfLength.KILOMETERS instead, please create a bug report at https://www.github.com/basilfx/homeassistant-biketrax/issues
2024-03-06 08:19:38.571 WARNING (MainThread) [homeassistant.const] LENGTH_METERS was used from biketrax, this is a deprecated constant which will be removed in HA Core 2025.1. Use UnitOfLength.METERS instead, please create a bug report at https://www.github.com/basilfx/homeassistant-biketrax/issues
2024-03-06 08:19:38.663 WARNING (MainThread) [homeassistant.const] SPEED_KILOMETERS_PER_HOUR was used from biketrax, this is a deprecated constant which will be removed in HA Core 2025.1. Use UnitOfSpeed.KILOMETERS_PER_HOUR instead, please create a bug report at https://www.github.com/basilfx/homeassistant-biketrax/issues

[basilfx]

Thank you.