[roll third_party/pigweed] pw_env_setup: Support Python 3.9

Currently there is no way to configure environment checks in
pw_env_setup, and often these checks are diagnosting downstream
adjustments rather than errors. Loosen up these checks to at least
permit Python 3.9, which is the default now in some distros.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/40362

third_party/pigweed Rolled-Commits: a77e5e7a1cfca3b..db0992d39c15747
Roller-URL: https://ci.chromium.org/b/8850130638242172368
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8850130638242172368
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ib2eb9c3d6fe33ba6833ca5939ec81d9f07151eb3
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/40664
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 a77e5e7..db0992d 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit a77e5e7a1cfca3b109e1bcf6536444080e6bee44
+Subproject commit db0992d39c15747bea91703d3349e318b5dd801a