[roll third_party/pigweed] pw_grpc: Fix some minor bugs

These were uncovered by static checkers on internal copybara import.

1. Two instances of Printf with a single argument
   (https://staticcheck.dev/docs/checks#SA1006).
1. One instance of ineffective break statement
   (https://staticcheck.dev/docs/checks#SA4011).
1. One Sprintf with missing argument.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/191831

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 460f429b01882c8..6b4f24a21d5f59f
Roller-URL: https://ci.chromium.org/b/8756269664733528769
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ia15894679ba5401795e72dd8c008ee81288b6b6b
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/191793
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 460f429..6b4f24a 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 460f429b01882c854e7805e9f6b2542b0fca44fc
+Subproject commit 6b4f24a21d5f59ff925f300d7a0fc23d7ea85071