Configure Dependabot to check for outdated actions used in workflows

Dependabot will periodically check the versions of all actions used in the repository's workflows. If any are found to
be outdated, it will submit a pull request to update them.

.github/dependabot.yml

@@ -0,0 +1,10 @@
+# See: https://docs.github.com/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file#about-the-dependabotyml-file
+version: 2
+
+updates:
+  # Configure check for outdated GitHub Actions actions in workflows.
+  # See: https://docs.github.com/code-security/dependabot/working-with-dependabot/keeping-your-actions-up-to-date-with-dependabot
+  - package-ecosystem: github-actions
+    directory: / # Check the repository's workflows under /.github/workflows/
+    schedule:
+      interval: daily