[roll third_party/pigweed] pw_env_setup: Remove f-strings from github_visitor

This file needs to be compatible with Python 2.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/210274
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 770fffc2d741fc5..7e07cfabb7a8768
Roller-URL: https://ci.chromium.org/b/8747726051361784865
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I16ccd935677f64086b4eb603e0c96a03c6ad8652
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/210210
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 770fffc..7e07cfa 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 770fffc2d741fc55e60d84acaa5f1c9fa90ce2cb
+Subproject commit 7e07cfabb7a8768c1676b138de7cc23996a3c924