Fix heat energy to be energy in not out (#1751)

* Fix heat energy to be energy in not out

* [pre-commit.ci lite] apply automatic fixes

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Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

apps/predbat/predheat.py

@@ -380,7 +380,7 @@ def run_simulation(self, volume_temp, heating_active, save="best", last_predict_
                 energy_now_out = heat_power_out * PREDICT_STEP / 60.0 / 1000.0
 
                 cost += energy_now_in * self.rate_import.get(minute_absolute, 0)
-                heat_energy += energy_now_out
+                heat_energy += energy_now_in
 
                 # 1.16 watts required to raise water by 1 degree in 1 hour
                 volume_temp += (heat_power_out / WATTS_TO_DEGREES / self.heat_volume) * PREDICT_STEP / 60.0