v.0.5.0: Sergry/api enhancements (#14)

* use Decimal when parsing floats and unquote artist name

* changed path paarmeters name

* modified tests

* renamed artists to artist

* added tags

* added pagination to the murals get method

* modified artist name - mural id global secondary index

* added a method that returns murals by an artist

* update request template for artists

* black and isort

* updated tests

* suppressed a warning

* put properties back

* removed unnecessary gsi

* Bump version: 0.4.0 -> 0.5.0