Move doc deploy action to the release workflow

[helen]

Description of the Change

Moves the doc build/deployment to the same workflow as the release to stable, since both run on master and are a signal of an impending new release. Realized this as I was changing the doc workflow to go back to running on master instead of develop. Also fixes a warning about version being deprecated in favor of node-version.

Alternate Designs

Leaving as-is, which is more resource intensive as it spins up two machines and runs npm install on both.

Benefits

Faster workflow run, less maintenance.

Possible Drawbacks

If we decide later they shouldn't run on the same trigger we'll have to split it back out.

Verification Process

n/a, basically hoping it'll work.

Checklist:

• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests passed.

Applicable Issues

See #191

Changelog Entry

n/a

[jeffpaul]

Looks good to me, good thinking on combining these as well!