[Bug] The foreign key constraint in the creation of `HazardFieldIntensity` is wrong

The table HazardFieldIntensity is created as below:

CREATE TABLE HazardFieldIntensity ( 
    hazard_field_node_id INTEGER, 
    intensity_type_id INTEGER, 
    intensity_value REAL, 
    CONSTRAINT fk_hazard_field_node_id FOREIGN KEY (hazard_field_node_id) REFERENCES HazardFieldNode (id), 
    CONSTRAINT fk_intensity_type_id FOREIGN KEY (intensity_type_id) REFERENCES IntensityType (intensity_type)
)

The last line should change to REFERENCES IntensityType (id) to avoid the error of sqlite3.IntegrityError: FOREIGN KEY constraint failed.

\rfc @ds @laurens