bugfix: fetch_series.m, fetch_series_by_api_link.m

src/fetch_series.m

@@ -56,7 +56,7 @@ default_api_base_url = 'https://api.db.nomics.world/v22/';
 default_editor_base_url = 'https://editor.nomics.world/api/v1/';
 
 p = inputParser;
-validStringInput = @(x) isstring(x) || ischar(x) || iscellstr(x);
+validStringInput = @(x) ischar(x) || iscellstr(x);
 p.addParameter('provider_code', '', validStringInput);
 p.addParameter('dataset_code', '', validStringInput);
 p.addParameter('series_code', '', validStringInput); 

src/fetch_series_by_api_link.m

@@ -40,7 +40,7 @@ function df = fetch_series_by_api_link(api_link, varargin) % --*-- Unitary tests
 default_editor_base_url = 'https://editor.nomics.world/api/v1/';
 
 p = inputParser;
-validStringInput = @(x) isstring(x) || ischar(x) || iscellstr(x);
+validStringInput = @(x) ischar(x) || iscellstr(x);
 p.addRequired('api_link');
 p.addOptional('dbnomics_filters', '',@ischar);
 p.addOptional('max_nb_series', NaN, @isnumeric);