Pass --shell to minikube docker-env

[kirs]

This fixes make dev-env for those developers who are using non-standard shell, for instance fish.

By default, minikube docker-env prints exports in the format of your shell. If your shell is fish and minikube docker-env is executed from a bash script, it will still print the export template in fish format. That makes the script break.

The solution is to pass --shell bash argument.

Side question: what minikube driver do you suggest use on Mac?

[aledbf]

/lgtm
/approve

[k8s-ci-robot]

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[aledbf]

@kirs thanks!

[ElvinEfendi]

Side question: what minikube driver do you suggest use on Mac?

@kirs I use default vm-driver which is virtualbox, haven't had any issue so far.