roll: third_party/pigweed pw_sensor: Add freeform extras field to sensor.yaml

Downstream users will require extra metadata that's not used in
Pigweed. We should allow each sensor to include this via the "extras"
key.

Original-BUG: b/293466822
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/248195
Original-Revision: b7246bf88df6aa030dec7b9510e7015b5035616c

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: 21933c60384c25..b7246bf88df6aa
Roll-Count: 1
Roller-URL: https://cr-buildbucket.appspot.com/build/8731319574170039393
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ia9baec7f74244bab85196bdde38e6445ad436df7
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/248641
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 21933c6..b7246bf 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 21933c60384c25d73dba60c90e74cc44d2a446de
+Subproject commit b7246bf88df6aa030dec7b9510e7015b5035616c