ci: add Dependabot configuration for GitHub Actions (#49)

## Description

Noticed the actions used in the workflows here are outdated, proposing a
Dependabot configuration to update - reference
https://docs.github.com/en/actions/security-guides/using-githubs-security-features-to-secure-your-use-of-github-actions#keeping-the-actions-in-your-workflows-secure-and-up-to-date

## Type of Change

<!-- Mark the relevant option with an 'x' -->

- [ ] Bug fix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] Documentation update
- [ ] Code refactoring
- [ ] Performance improvement
- [ ] Test updates

## Checklist

- [x] My code follows the code style of this project
- [x] I have performed a self-review of my own code
- [x] I have commented my code, particularly in hard-to-understand areas
- [ ] I have updated the documentation accordingly
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published

## Additional Notes

Suggest enabling
https://docs.github.com/en/code-security/dependabot/working-with-dependabot/about-dependabot-on-github-actions-runners#enabling-or-disabling-for-your-repository
as well

---------

Co-authored-by: Alexander Dines <160077924+dines-rl@users.noreply.github.com>

Author: ScottBrenner

.github/dependabot.yml

@@ -0,0 +1,14 @@
+version: 2
+updates:
+  # Enable version updates for GitHub Actions
+  - package-ecosystem: "github-actions"
+    # Look for GitHub Actions workflows in the `root` directory
+    directory: "/"
+    # Check for updates once a week
+    schedule:
+      interval: "weekly"
+
+  - package-ecosystem: "npm"
+    directory: "/"
+    schedule:
+      interval: "weekly"