You need to fix the readme file syntax from _ to * on line Create workflows that enable you to use Continuous Integration (CI) for your projects. in readme file on the ci branch then it will update to next step and keep the file from workflow file from step 1 same
hope this works for you it did for me

Did you get the build error in the merge box? GitHub really doesn't like the YAML in this workflow, and if you don't get it exactly right the tests don't run so you never see the build error. Following the build error is what leads you to the solution, so you need to run the right tests to trigger the error before you can move on.
The solution that worked for me was deleting every comment line and empty line, then going through it line-by-line to correct the indentation (you can find and example of correct indentation here: https://stackoverflow.com/a/72877883). After that the tests ran and the build error appeared in the merge box.