[roll third_party/pigweed] pw_uart: Create OWNERS

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/200750

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 15303ba92faa0dd..16ca90925a98bdc
Roller-URL: https://ci.chromium.org/b/8752224453353815953
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ib05623f2ba07f8935553610fe4cd35e4a1bb7482
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/200893
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 15303ba..16ca909 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 15303ba92faa0dd3d5be144dfaa5317fa259d400
+Subproject commit 16ca90925a98bdcbe294618973adff00e2649853