Update search_by_keyword.go

[faizanbashir]

Fixed error in the service.Search.List parameter as []string value is required.

The code returns the below error:

./search_by_keywords.go:33:30: cannot use "id,snippet" (untyped string constant) as []string value in argument to service.Search.List

I have update the parameter to a []string{"id, snippet"} which has fixed the error.

[google-cla[bot]]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.