[feature] Create a cache file to not download the weather data from PVGIS each time

Summary

Create a cache file to not download the weather data from PVGIS each time if the parameters longitude and latitude did not change.

Current behavior

Each time the main.py file is lauched, data are downloaded from PVGis.

Desired behavior

See Summary

Sources

n/a

Linked features or branches

Issue #32 (closed but should not have been closed)

#74