Unpin shellcheck

[lzap]

I had to pin shellcheck to version 0.10 because version 0.11 introduced some new checks which are failing. This was done in: #4803

Changes: https://github.com/koalaman/shellcheck/blob/d09551a4e6fa73d74f25b02f9322d0bf9fc602a5/CHANGELOG.md?plain=1#L11-L21

Let's either unpin it, or pin to 0.11 in a more controlled PR.