Refresh Access Token
POST https://api-sandbox.astra.finance/v1/oauth/token
Request Body
[{"name"=>"grant_type", "value"=>"refresh_token", "datatype"=>"string"}, {"name"=>"refresh_token", "value"=>"your_user_refresh_token", "datatype"=>"string"}, {"name"=>"redirect_uri", "value"=>"your_redirect_uri", "datatype"=>"string"}]