format: Ensure that files end with a newline

This is needed in order to land http://pwrev.dev/269393.

Change-Id: I9aa3785fff01888398f526770c2bed0743418818
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/269452
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Commit-Queue: Michael Brase <mbrase@google.com>
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ted Pudlik <tpudlik@google.com>
diff --git a/pw_async_bench/public/pw_async_bench/base.h b/pw_async_bench/public/pw_async_bench/base.h
index 6343b99..74774d2 100644
--- a/pw_async_bench/public/pw_async_bench/base.h
+++ b/pw_async_bench/public/pw_async_bench/base.h
@@ -25,4 +25,4 @@
   std::string value;
 };
 
-}  // namespace pw::async_bench
\ No newline at end of file
+}  // namespace pw::async_bench