[roll third_party/pigweed] pw_log_zephyr: Add EOT character to help with detokenizing on Zephyr

Zephyr console may output raw text along with the tokenized messaging.
This causes issues in determining when the end of a base64 message
occurs to process a token. Adding an EOT to the end of a base64 message
helps encapsulate the entire token or when we're receiving a token.
Upon receiving the EOT the token can be fully decoded without errors.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/153751

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 1bd7446c44e8105..4037d862e8a8584
Roller-URL: https://ci.chromium.org/b/8776906336189123809
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I95bdcc9228fbbfc4f8713296fe6413c1c25269c2
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/153772
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 1bd7446..4037d86 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 1bd7446c44e81058418c9b2c000ce296dcd7b7ea
+Subproject commit 4037d862e8a8584da6dd5b57123870809c2c66e3