TBR: playground: Fix Dockerfile for bin to devtools/bin move.

https://vanadium-review.googlesource.com/#/c/9511/

Change-Id: I731e760a8262a5df2cbc78c4d595b48ebedd6354
diff --git a/go/src/playground/Dockerfile b/go/src/playground/Dockerfile
index 8af2303..e083a31 100644
--- a/go/src/playground/Dockerfile
+++ b/go/src/playground/Dockerfile
@@ -16,7 +16,7 @@
 ENV V23_ROOT /usr/local/vanadium
 ENV GOPATH $V23_ROOT/release/projects/playground/go
 ENV VDLPATH $GOPATH
-ENV PATH $V23_ROOT/release/projects/playground/go/bin:$V23_ROOT/release/go/bin:$V23_ROOT/bin:$PATH
+ENV PATH $V23_ROOT/release/projects/playground/go/bin:$V23_ROOT/release/go/bin:$V23_ROOT/devtools/bin:$PATH
 
 # Setup Vanadium.
 # Note: This will be cached! If you want to re-build the docker image using