ci: reduce dependabot frequency, fix conflicting groups

Author: tronghn

.github/dependabot.yml

@@ -4,18 +4,16 @@ updates:
     # Files stored in repository root
     directory: "/"
     schedule:
-      interval: "daily"
-    open-pull-requests-limit: 10
+      interval: "weekly"
     groups:
-      github:
+      gradle-dependencies:
         patterns:
           - "*"
   - package-ecosystem: github-actions
     directory: "/"
     schedule:
-      interval: daily
-    open-pull-requests-limit: 10
+      interval: "weekly"
     groups:
-      github:
+      github-actions:
         patterns:
           - "*"