roll: third_party/pigweed: roll: Fuchsia SDK

*  Restrict the Fuchsia build to Linux, since the Fuchsia SDK no
   longer supports MacOS.
*  Add support to cipd_repository for fetching different CIPD
   versions on different platforms, to pin the MacOS version.

Original-Bug: 258836641
Original-Bug: 353749536
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/223593
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 29eecebfec5d803..7bd3905ad725850
Roller-URL: https://ci.chromium.org/b/8742125032077603265
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I67cfd514c2c58f1e17e4e3197e218cee34bbf1a1
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/223819
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: 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 29eeceb..7bd3905 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 29eecebfec5d80382098a66d7db0c4593352c80d
+Subproject commit 7bd3905ad725850781afbfd4e52ff106b5a749d8