[roll third_party/pigweed] pw_web: Fix TypeScript warnings in web_serial_transport.ts

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/164591

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 19c1ff4a13b3049..13da8c012a5e82b
Roller-URL: https://ci.chromium.org/b/8773200954274887857
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I9957030a6c49b63f6a310072b9d0a844022fed23
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/164610
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 19c1ff4..13da8c0 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 19c1ff4a13b304935a01cd01abb483411953cf6d
+Subproject commit 13da8c012a5e82b146b283fbcea4c5a8eeac91d7