Update Dependabot config

- limit the number of open PRs
- check for actions updates less often b/c this is less critical

.github/dependabot.yml

@@ -7,10 +7,12 @@ updates:
   - package-ecosystem: "github-actions"
     directory: "/"
     schedule:
-      interval: "daily"
+      interval: "weekly"
+    open-pull-requests-limit: 5
 
-  # Maintain dependencies for npm
+  # Maintain dependencies for Go
   - package-ecosystem: "gomod"
     directory: "/"
     schedule:
       interval: "daily"
+    open-pull-requests-limit: 5