Keep GitHub Actions up to date with GitHub's Dependabot

Fixes software supply chain safety warnings like at the bottom right of
https://github.com/TheAlgorithms/JavaScript/actions/runs/8960545794

* [Keeping your actions up to date with Dependabot](https://docs.github.com/en/code-security/dependabot/working-with-dependabot/keeping-your-actions-up-to-date-with-dependabot)
* [Configuration options for the dependabot.yml file - package-ecosystem](https://docs.github.com/en/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file#package-ecosystem)

Author: cclauss

.github/dependabot.yml

@@ -0,0 +1,8 @@
+# Keep GitHub Actions up to date with Dependabot...
+# https://docs.github.com/en/code-security/dependabot/working-with-dependabot/keeping-your-actions-up-to-date-with-dependabot
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"