housekeeping: Keep github actions up to date as well.

Author: glennawatson

.github/dependabot.yml

@@ -6,3 +6,8 @@ updates:
     interval: daily
     time: "00:00"
   open-pull-requests-limit: 20
+- package-ecosystem: "github-actions"
+  directory: "/"
+  schedule:
+    # Check for updates to GitHub Actions every weekday
+    interval: "daily"