ci: Ensure SSH client is installed

[jmgate]

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It's needed by the Semantic Release workflow to sign the releases. I'm not sure why this step wasn't needed in the past, but within the past week the Semantic Release job has failed intermittently, meaning certain runners using ubuntu-latest have it installed, while others do not.

Here's an example of a failing job.

@jcox10, does this solution make sense to you?

Summary by Sourcery

CI:

• Install openssh-client via apt-get in the semantic-release job