config: dependabot update quarterly

Signed-off-by: nstarman <nstarman@users.noreply.github.com>

Author: nstarman

.github/dependabot.yml

@@ -4,7 +4,7 @@ updates:
   - package-ecosystem: "github-actions"
     directory: "/"
     schedule:
-      interval: "monthly"
+      interval: "quarterly"
     groups:
       actions:
         patterns: