pw_tls_client: Add comma to build file

Change-Id: I2f93b41b1dc9d323f4e9dcb8f847bab774012d30
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/50461
Pigweed-Auto-Submit: Rob Mohr <mohrr@google.com>
Reviewed-by: Yecheng Zhao <zyecheng@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/pw_tls_client/BUILD b/pw_tls_client/BUILD
index 5239c8f..d23ebc6 100644
--- a/pw_tls_client/BUILD
+++ b/pw_tls_client/BUILD
@@ -56,5 +56,5 @@
     deps = [
         "//pw_bytes",
         "//pw_status",
-    ]
+    ],
 )