[roll third_party/pigweed] pw_watch: Unpin watchdog as version 2.1.0 fixes the Mac behavior

See https://github.com/gorakhargosh/watchdog/pull/779

No-Docs-Update-Reason: bug fix
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/48521

third_party/pigweed Rolled-Commits: 6455293368c5dd3..249497a97d2b444
Roller-URL: https://ci.chromium.org/b/8844773586701269969
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8844773586701269969
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ia9d62e56cc83dfb414abc54351a38a8b89efed60
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/48582
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 6455293..249497a 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 6455293368c5dd3a5a52b587ec5e74eb486dea8d
+Subproject commit 249497a97d2b4444bf5c27761bb164bf8c800ea6