chore: Use dependabot to update github-actions (#812)

* Update github-actions with dependabot

Following instructions from [this Github help page](https://docs.github.com/en/code-security/dependabot/working-with-dependabot/keeping-your-actions-up-to-date-with-dependabot), configuring dependabot to check for updates to GitHub Actions such as codeql.

Signed-off-by: Anna Kornfeld Simpson <AnnaKornfeldSimpson@users.noreply.github.com>

Author: AnnaKornfeldSimpson

.github/dependabot.yml

@@ -9,3 +9,8 @@ updates:
     directory: "/" # Location of package manifests
     schedule:
       interval: "daily"
+
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"