[roll third_party/pigweed] pw_log: Update proto

- Update proto to use a single bytes field for optionally tokenized
  fields.
- Start with a minimal set of fields, but document fields planned for
  future expansion.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/47780

third_party/pigweed Rolled-Commits: de20d74135441e7..0d4c9169cda2f4a
Roller-URL: https://ci.chromium.org/b/8844968328668800880
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8844968328668800880
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I131c0fd82429c560321dff02039fd85c46134676
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/48344
Reviewed-by: 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 de20d74..0d4c916 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit de20d74135441e76593ea10ab10a4ef3031e6a09
+Subproject commit 0d4c9169cda2f4af2b6a7a09197cbe7fc604d713