Check for signed-off-by doesn't ignore comments

Same as https://github.com/conventional-changelog/commitlint/issues/1809
Fix: https://github.com/conventional-changelog/commitlint/pull/2098

Can we get this change in the action? I am also getting the same issue.

![Screenshot from 2021-07-01 14-24-04](https://user-images.githubusercontent.com/22993933/124096245-08975c00-da78-11eb-8dee-5aa0f2ede177.png)

