Fix syntax error in YAML file of rapids CI

[toshihikoyanase]

Motivation

This PR will resolve the syntax error in rapids.yaml.
As we can see the following CI result, the Run examples block is not correctly indented:

GitHub Actions .github/workflows/rapids.yml
Invalid workflow file
You have an error in your yaml syntax on line 12

Description of the changes

• Fix the indent of the lines in rapids.yaml

[toshihikoyanase]

I don't think the workflow name in rapids.yaml should be base. Can I rename it to rapids in this PR?

[y0z]

LGTM. To fix CI at first, I merged this PR and will make another PR to rename this.