Fix subregions search

[ClaroHenrique]

This PR adjusts the search to consider all subregions passed in the get arguments. Before that, only the last subregion was used in the search.

Example:

Before this PR

 Cities of multiple states were returned, even with the "Maranhão" state being passed has parameter.

After

 Only the city inside the "Maranhão" state is returned.

[juliohm]

Thank you @ClaroHenrique for these great contributions and PR descriptions, they help a lot. 💯