Fix units for Req Latency in output to seconds (#113)

`request_latency()` returns time in seconds not ms.

Signed-off-by: Sai Sindhur Malleni <smalleni@redhat.com>

Author: smalleni

src/guidellm/benchmark/output.py

@@ -302,7 +302,7 @@ def print_benchmarks_stats(self):
             "Requests Concurrency",
             "Output Tok / sec",
             "Total Tok / sec",
-            "Req Latency (ms)\n(mean / median / p99)",
+            "Req Latency (sec)\n(mean / median / p99)",
             "TTFT (ms)\n(mean / median / p99)",
             "ITL (ms)\n(mean / median / p99)",
             "TPOT (ms)\n(mean / median / p99)",