[libc++] Trigger rebuild of the Docker image so we get a new nightly Clang

GitOrigin-RevId: 5c454033dd622bc48986dc8025f4936b5fa54975
diff --git a/utils/ci/Dockerfile b/utils/ci/Dockerfile
index 653fef0..cffb735 100644
--- a/utils/ci/Dockerfile
+++ b/utils/ci/Dockerfile
@@ -37,7 +37,7 @@
 # CI builders to rebuild their copy of the Docker image. This is not a great
 # solution, however without that, the CI builders will keep the same cached
 # Docker image forever.
-RUN echo 2
+RUN echo 3
 
 RUN apt-get update && apt-get install -y bash curl