Optimize binary size

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

backend/Dockerfile

@@ -1,4 +1,5 @@
-FROM rust AS builder
+FROM rust:alpine AS builder
+RUN apk add --no-cache pkgconf musl-dev openssl-dev
 
 WORKDIR /usr/src/qrust
 
@@ -12,7 +13,7 @@ RUN rm -rf src
 COPY . .
 RUN cargo build --release
 
-FROM frolvlad/alpine-glibc AS backend
+FROM alpine AS backend
 
 WORKDIR /usr/src/qrust