pw_env_setup: Update clang next version

Make toolchain roll canary builders to target the latest clang toolchain
revision: e6549b8036089f20c6ac01e644a544aa2b231ca8

Bug: 366374135
Change-Id: Id9306e62801e78d090919fa6ba0249000bf5ec34
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/241136
Pigweed-Auto-Submit: Prabhu Karthikeyan Rajasekaran <prabhukr@google.com>
Docs-Not-Needed: Prabhu Karthikeyan Rajasekaran <prabhukr@google.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Reviewed-by: Rob Mohr <mohrr@google.com>
Commit-Queue: Prabhu Karthikeyan Rajasekaran <prabhukr@google.com>

pw_env_setup/py/pw_env_setup/cipd_setup/clang_next.json

@@ -10,7 +10,7 @@
         "windows-amd64"
       ],
       "tags": [
-        "git_revision:3928edecfbd116d56bbe7411365d50bb567380a1"
+        "git_revision:e6549b8036089f20c6ac01e644a544aa2b231ca8"
       ],
       "version_file": ".versions/clang.cipd_version"
     }