Update Static Site Template to Support Dynamic Ruby/Node versions

[btylerburton]

User Story

In order to allow for flexibility across projects, datagovteam wants to support passing the ruby and node version required to the parent static-site build template.

Acceptance Criteria

[ACs should be clearly demoable/verifiable whenever possible. Try specifying them using BDD.]

• GIVEN I have a GH action that calls the shared static-site-build-template
  AND I want to pass a custom ruby/node version
  WHEN I build the site
  THEN I want to see it use my custom ruby/node version

Background

Related:

• update ruby and gems data-strategy#336

Reference:

• https://docs.github.com/en/actions/sharing-automations/reusing-workflows#creating-a-reusable-workflow

Security Considerations (required)

[Any security concerns that might be implicated in the change. "None" is OK, just be explicit here!]

Sketch

• Pass ruby and node versions as inputs to reusable workflow

[ryanwoldatwork]

The re-use is a nice idea, but also creates a coupling, and thus, a coordination cost.
For something specific like a build script, I'd just hard code it.