Missing expression syntax or escaping for if: ! expr is not detected

[gschwaer]

The following is not validated (from github docs):

You must always use the ${{ }} expression syntax or escape with '', "", or () when the expression starts with !, since ! is reserved notation in YAML format. For example:

if: ${{ ! startsWith(github.ref, 'refs/tags/') }}

For more information, see "Expressions."

Currently, this will not be detected as a bug:

if: ! startsWith(github.ref, 'refs/tags/')

The runner will abort with:

The workflow is not valid. .github/workflows/build.yml: (Line: 42, Col: 42, Idx: 420) - (Line: 42, Col: 43, Idx: 421): While parsing a tag, did not find expected tag URI.

It should be linted as an error.

[felipesu19]

Switched this to a bug, since i think that fits better