Updated gh-actions for set-output deprecation

[flooose]

Note: Delete the description statements, complete each step. None are optional, but can be justified as to why they cannot be completed as written. Provide known gaps to testing that may raise the risk of merging to production.

Summary

1. aws-actions/configure-aws-credentials@v1 - Can be replaced with @v2; see Update action to use node 16 aws-actions/configure-aws-credentials#489
   Already correct
2. marvinpinto/action-inject-ssm-secrets - No apparent updates forthcoming; the maintainer appears to be absent. This is widely used: https://github.com/search?q=org%3Adepartment-of-veterans-affairs+action-inject-ssm-secrets&type=code
   Already correct
3. slackapi/slack-github-action - Fixable by moving to version 1.23.0
   Already correct
4. EndBug/add-and-commit - Fixable by moving to v9
5. Add entry to dependabot.yml for gh-actions updates
   Already correct

Related issue(s)

• Third-party set-output usage va.gov-team#55037

Testing done

Screenshots

Note: Optional

[timcosgrove]

Approved