validation of id

[amarao]

I've just got a reprimand from Github actions whilst actionlint was totally OK:

The identifier 'Set production tag (semantic)' is invalid. IDs may only contain alphanumeric characters, '_', and '-'. IDs must start with a letter or '_' and and must be less than 100 characters.

I believe Actionlint may validate steps ID to match Github requirements.

Example of a bad workflow:

"on":
  push:

jobs:
  foo:
    steps:
      - id: Set production tag (semantic)
        run: echo hello

Sorry for the issue instead of a PR, Go is not my strongest.

[rhysd]

Thanks for your suggestion. It should be detected by actionlint.