[roll third_party/pigweed] pw_ide: Remove Path.with_stem() uses

Path.with_stem() was added in Python 3.9, and we're trying to support
Python 3.8.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/111075

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: f90b6ee1b9d7182..1261f30c84f7b68
Roller-URL: https://ci.chromium.org/b/8802380060721147153
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I2bea5a5592a8275f8d522703b36b7237abff9f9b
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/111350
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Bot-Commit: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index f90b6ee..1261f30 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit f90b6ee1b9d71823b39e2a771e87a525757639a5
+Subproject commit 1261f30c84f7b68405d4601730980ac87cc56a7b