fix error due to breaking change in http 0.13

[renntbenrennt]

As you can see from below screenshot:

And further discussion on solution can be found here: https://github.com/dart-lang/http/issues/538

The breaking change of the http makes all the request originally in string, now must be Uri, if the user's Flutter is 2.0+

In this commit I was using Uri.parse to refactor all the place using http package method, changing the string to Uri.

[diegoveloper]

Thanks for the contribution! @SeasonLeee