Move SVN installation to seperate step.

[peterwilsoncc]

Is your enhancement related to a problem? Please describe.

The action currently installs SVN in the same step as running the deploy. The result of this is that in action runs the SVN installation log and the deploy log show in the same section of the logs, for example see https://github.com/10up/Ad-Refresh-Control/actions/runs/20730723849/job/59517744376

Describe the solution you'd like

Move the SVN installation in to a separate step so the two actions are displayed in logs as independent steps. This will ensure the SVN install log and the SVN commit log are able to be reviewed in their own section.

It will also clarify the failure point if the action fails: whether it was the SVN install or the deployment.

Designs
N/A

Describe alternatives you've considered
In my own repos, I install SVN as a separate task to show the logs in their own section. As it's possible to do via a workaround, we could do nothing. See https://github.com/peterwilsoncc/local-twemoji/blob/main/.github/workflows/wporg-deploy.yml#L15

Additional context
If this works as expected, the same change should also be made on the plugin deploy.

[peterwilsoncc]

This isn't possible with composite actions, even with multiple steps the log will be within a single entry. See this action run in a test repo.

Multiple steps can be done in reusable workflows but that's a more significant and riskier change.