Upgrade github.com/mvdan/sh to v3.9.0
What does this MR do?
Upgrades dependency mvdan/sh dependency.
Why was this MR needed?
Fixes #36964 (closed) (https://github.com/mvdan/sh/issues/1076).
What's the best way to test this MR?
Issue from #36964 (closed) fixed.
What are the relevant issue numbers?
Closes #36964 (closed)