[roll third_party/pigweed] pw_protobuf: Add some type annotations

These would have helped me orient in the code when I was working on it.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/110636

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 55f7eca400f7cdb..2cc1c5bbc85aea5
Roller-URL: https://ci.chromium.org/b/8802558246467037649
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Iea3f161f77c07c77979e9ecac89ecd4e56967c8f
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/110960
Bot-Commit: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 55f7eca..2cc1c5b 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 55f7eca400f7cdb82e1f2327096f7c3c48365788
+Subproject commit 2cc1c5bbc85aea5142aa5bd38abd0e0786f4e6ad