chore: update dependabot configuration for GitHub Actions (#255)

Author: chorrell

.github/dependabot.yml

@@ -4,3 +4,11 @@ updates:
     directory: "/"
     schedule:
       interval: "weekly"
+      day: "monday"
+      time: "09:30"
+      timezone: "America/Toronto"
+      pull-request-branch-name:
+        separator: "/"
+      commit-message:
+        prefix: "ci"
+        include: "scope"