ci: group dependabot github action bump (#79)

reduce pull request noise for github action bump

Author: kruskall

.github/dependabot.yml

@@ -14,21 +14,9 @@ updates:
 
   # GitHub actions
   - package-ecosystem: "github-actions"
-    directory: "/"
-    reviewers:
-      - "elastic/observablt-ci"
-    schedule:
-      interval: "weekly"
-      day: "sunday"
-      time: "22:00"
-    groups:
-      github-actions:
-        patterns:
-          - "*"
-
-  # GitHub composite actions
-  - package-ecosystem: "github-actions"
-    directory: "/.github/actions/env-install"
+    directories:
+      - "/"
+      - "/.github/actions/*"
     reviewers:
       - "elastic/observablt-ci"
     schedule: