Fix GitHub Actions schema violations for non-string default values

[Coderrob]

Description:
I created a Action schema validation process that does self-documentation from the Action's yaml definition. In running the tool on the setup-java repo it failed validation.

The default input property fields expect a string value and in two locations within the action.yml there are boolean values provided as defaults.

Related issue:
TODO

Check list:

• Mark if documentation changes are required.
• Mark if tests were added or updated to cover the changes.