[core] add const for litre per hour (#17389)

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

esphome/components/kamstrup_kmp/sensor.py

@@ -21,6 +21,7 @@ from esphome.const import (
     UNIT_EMPTY,
     UNIT_KELVIN,
     UNIT_KILOWATT,
+    UNIT_LITRE_PER_HOUR,
 )
 
 CODEOWNERS = ["@cfeenstra1024"]
@@ -37,7 +38,6 @@ CONF_TEMP2 = "temp2"
 CONF_TEMP_DIFF = "temp_diff"
 
 UNIT_GIGA_JOULE = "GJ"
-UNIT_LITRE_PER_HOUR = "l/h"
 
 # Note: The sensor units are set automatically based un the received data from the meter
 CONFIG_SCHEMA = (

esphome/const.py

@@ -1255,6 +1255,7 @@ UNIT_KILOVOLT_AMPS_REACTIVE_HOURS = "kvarh"
 UNIT_KILOWATT = "kW"
 UNIT_KILOWATT_HOURS = "kWh"
 UNIT_LITRE = "L"
+UNIT_LITRE_PER_HOUR = "L/h"
 UNIT_LITRE_PER_SECOND = "L/s"
 UNIT_LUX = "lx"
 UNIT_MEGAJOULE = "MJ"