Fix Rails 5 deprecation warning for get request spec

DEPRECATION WARNING:

`ActionDispatch::IntegrationTest` HTTP request methods will accept only
the following keyword arguments in future Rails versions:
params, headers, env, xhr, as

Examples:

    get '/profile',
      params: { id: 1 },
      headers: { 'X-Extra-Header' => '123' },
      env: { 'action_dispatch.custom' => 'custom' },
      xhr: true,
      as: :json

Author: csexton

spec/requests/api_spec.rb

@@ -18,7 +18,7 @@ def headers_with_token(token)
         stub_request(:get, "https://account.radiusnetworks.com/auth/radius/user.json?oauth_token=123")
           .to_return(status: 200, body: json)
 
-        get api_index_path, nil, headers_with_token("123")
+        get api_index_path, params: {}, headers: headers_with_token("123")
 
         expect(response.status).to be 200
       end