Add step temperature - Issue #311 (#355)

* Add step temperature in config

* All testus ok

* Keep the step of the VTherm and not the step of the underlying

* Release 5.4.0

---------

Co-authored-by: Jean-Marc Collin <jean-marc.collin-extern@renault.com>

tests/test_bugs.py

@@ -591,6 +591,7 @@ async def test_bug_272(
         domain=DOMAIN,
         title="TheOverClimateMockName",
         unique_id="uniqueId",
+        # default value are min 15°, max 30°, step 0.1
         data=PARTIAL_CLIMATE_CONFIG,  # 5 minutes security delay
     )
 
@@ -623,6 +624,8 @@ async def test_bug_272(
         assert entity.name == "TheOverClimateMockName"
         assert entity.is_over_climate is True
         assert entity.hvac_mode is HVACMode.OFF
+        # The VTherm value and not the underlying value
+        assert entity.target_temperature_step == 0.1
         assert entity.target_temperature == entity.min_temp
         assert entity.is_regulated is True