Set the workdir after user switching

Dockerfile

@@ -5,6 +5,7 @@ ARG GODOT_VERSION="4.3-stable"
 ARG BUTLER_VERSION="15.12.0"
 
 USER root
+WORKDIR /root
 
 RUN apt-get update \
     && apt-get install -y git libfontconfig1 \
@@ -24,6 +25,8 @@ RUN chmod +x /usr/bin/godot_* /usr/bin/butler_*
 RUN emsdk_install /usr/bin
 
 USER rustbuilder
+WORKDIR /home/rustbuilder
+
 RUN godot_install $GODOT_VERSION $PLATFORM
 RUN butler_install $BUTLER_VERSION