Update Dockerfile

Dockerfile

@@ -21,11 +21,11 @@ RUN chmod +x install_fmt.sh
 # Install Rust & Cargo
 RUN ./install_rustup.sh
 
-# Now act as `user`
-USER user
-
 # Install Rust nightly
 RUN ./install_rust_nightly.sh
 
 # Install rustfmt-nightly
 RUN ./install_fmt.sh
+
+# Now act as `user`
+USER user
\ No newline at end of file