[no ci] Run benchmark less frequent (every 4 hours) (#51)

Signed-off-by: Huy Do <huydhn@gmail.com>

Author: huydhn

.github/workflows/vllm-benchmark.yml

@@ -2,8 +2,8 @@ name: vLLM Benchmark
 
 on:
   schedule:
-    # Run every 2 hours
-    - cron: '0 */2 * * *'
+    # Run every 4 hours
+    - cron: '0 */4 * * *'
   workflow_dispatch:
     inputs:
       vllm_branch: