[roll third_party/pigweed] pw_env_setup: Fix pip upgrading on Mac

When bootstrapping with the system python on Mac, __PYVENV_LAUNCHER__
is set in the environment which causes pip installs in the virtualenv
to not work properly. This was fixed for ninja installs but not for
other calls to pip such as the initial upgrade of pip itself.

Fix this by always running pip in the virtualenv during bootstrap.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/58600

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 00ba31c51c7a90e..8552c61aaccdd57
Roller-URL: https://ci.chromium.org/b/8837733108837503937
Cq-Cl-Tag: roller-builder:pigweed-sample-project-roller
Cq-Cl-Tag: roller-bid:8837733108837503937
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I0209be61d2d576819abee31347631a73e7296d42
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/sample_project/+/58660
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 00ba31c..8552c61 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 00ba31c51c7a90ebfffec954b1dc28db015bfef3
+Subproject commit 8552c61aaccdd5742c2f53d009eeb5b5200fd9a7