multiply losses by sum duration steps (#520)

## Issue addressed
Solves #<issue number>

## Code of conduct
- [x] I HAVE NOT added sensitive or compromised (test) data to the
repository.
- [x] I HAVE NOT added vulnerabilities to the repository.
- [x] I HAVE discussed my solution with (other) members of the RA2CE
team.

## What has been done?
Explain how you addressed the resolution of the related issue, what
choices you made and why.

### Checklist
- [x] Code is formatted using our custom `black` and `isort`
definitions.
- [x] Tests are either added or updated.
- [x] Branch is up to date with `master`.
- [x] Updated documentation if needed.

## Additional Notes (optional)
Add any additional notes or information that may be helpful.

ra2ce/analysis/losses/losses_base.py

@@ -433,7 +433,7 @@ def _calculate_production_loss_per_capita(
             vlh_trip_type_event = sum(
                 (
                     intensity_trip_type
-                    * duration
+                    * duration**2
                     * loss_ratio
                     * occupancy_trip_type
                     * self.production_loss_per_capita_per_hour
@@ -443,6 +443,7 @@ def _calculate_production_loss_per_capita(
                     duration_steps, functionality_loss_ratios
                 )
             )
+
             vehicle_loss_hours.loc[
                 [vlh_row.name], f"vlh_{trip_type}_{hazard_col_name}"
             ] = vlh_trip_type_event

tests/test_data/losses/csv_data_for_losses/results_test_calc_vlh.csv

@@ -4,4 +4,4 @@ link_id,link_type,vlh_business_EV1_ma,vlh_commute_EV1_ma,vlh_EV1_ma_total
 3,motorway,196291.6,448666.6,0.0
 4,motorway,458916.6,1835666.6,0.0
 5,motorway,729750.0,729750.0,0.0
-6,motorway,3.333333e+01,3.333333e+01,0.0
+6,motorway,126.66666666666666,126.66666666666666,0.0