[roll third_party/pigweed] pw_unit_test: Fix forward for result sink bug

Fixes a bug with http://pwrev/111472 that resulted in tests always
failing to run locally.

Tested: Using pw watch locally, which reproduced the bug and confirmed the fix works.
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/112010

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 5e6ec727faa4923..578c05bd7f41510
Roller-URL: https://ci.chromium.org/b/8801930004325632529
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I1943caa7dcb8652bca3c49327d8dff86b250bb07
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/112072
Bot-Commit: 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 5e6ec72..578c05b 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 5e6ec727faa4923dd8944d47e980c6db22418e62
+Subproject commit 578c05bd7f415100a46fde406c69f084bf86602b