Automatically install yq on Windows runners

[bartekpacia]

Quick backport of #332

kudos to @penkzhou

[solsticedhiver]

Well, this pulls another dependency, that is bash. Let me explain.

I am trying to test a github action using act. To do so, I am running act on Windows with act -P windows-latest=-self-hosted avoiding the use of docker.

I rewrote some steps to use powershell instead of bash, because I don't have bash installed in my Windows VM. but now the step using subosito/flutter/action fails with Make yq tool available on Windows runners.

I thought I could avoid that by installing yq. But that does not help.
So before instaling yq, check it is not already installed, and/or avoid using bash, when powershell is possible...

[bartekpacia]

Hi @solsticedhiver, sorry about this.

I'll be glad to review a PR fixing this!

[solsticedhiver]

oh wait. I am seeing that you are using bash for the rest too. That would be too complicated.

Never mind.