fix cannot produce pro-macro as the target x86_64-unknown-linux-musl does not support these crate types from rust-lang/cargo#7563

Author: Evian-Zhang

backend/Dockerfile

@@ -3,7 +3,7 @@ FROM rust:alpine AS builder
 WORKDIR /app
 
 COPY . .
-RUN cargo build --release
+RUN RUSTFLAGS="-C target-feature=-crt-static" cargo build --release
 
 FROM alpine