Warning when using template expression as values

[winstliu]

For example:

jobs:
- ${{ each version in parameters.versions }}:
  - job: ${{ version }}

will mark ${{ version }} with the warning String does not match the pattern of "^[_A-Za-z0-9]*$".

There's also

${{ each step in parameters.steps }}:
  - ${{ step }}

which yields Incorrect type. Expected "object" for ${{ step }}.