Configure Dependabot to check for outdated actions used in workflows

The addition of this configuration file will cause Dependabot to periodically check the versions of the GitHub Actions
actions dependencies of the repository's workflows. If any are found to be outdated, it will submit a pull request to
update them.

Author: per1234

.github/dependabot.yml

@@ -0,0 +1,16 @@
+# See: https://docs.github.com/en/code-security/supply-chain-security/configuration-options-for-dependency-updates#about-the-dependabotyml-file
+version: 2
+
+updates:
+  # Configure check for outdated GitHub Actions actions in workflows.
+  # Source: https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/assets/dependabot/README.md
+  # See: https://docs.github.com/en/code-security/supply-chain-security/keeping-your-actions-up-to-date-with-dependabot
+  - package-ecosystem: github-actions
+    directory: /.github/workflows/
+    assignees:
+      - per1234
+    labels:
+      - "topic: infrastructure"
+    open-pull-requests-limit: 100
+    schedule:
+      interval: daily