fix docker

Author: archeoss

dockerfiles/alpine/Dockerfile

@@ -40,7 +40,6 @@ RUN echo "// if you see this, the build broke" > backend/src/lib.rs \
   && echo "fn main() {println!(\"if you see this, the build broke\")}" > backend/src/main.rs \
   && echo "fn main() {println!(\"if you see this, the build broke\")}" > frontend/build.rs \
   && echo "// if you see this, the build broke" > cli/src/lib.rs \
-  && echo "// if you see this, the build broke" > proc_macro/src/lib.rs \
   && cargo build-backend --profile=$BUILD_PROFILE --target=$BUILD_TARGET
 
 COPY . ./