Add multi-stage build for Docker

Dockerfile

@@ -1,15 +1,13 @@
-FROM python:3.10.13-slim-bookworm
+FROM python:3.10-slim AS builder
 
-WORKDIR /app
+RUN apt-get update
+RUN apt-get install -y --no-install-recommends build-essential gcc
+RUN python -m pip install --upgrade pip
 
 ENV VIRTUAL_ENV=/venv
 RUN python -m venv --copies $VIRTUAL_ENV
 ENV PATH="$VIRTUAL_ENV/bin:$PATH"
 
-RUN apt-get update
-RUN apt-get install gcc python3-dev -y
-RUN python -m pip install --upgrade pip
-
 # Install dependencies before ISAR to cache pip installation
 RUN mkdir -p src
 COPY setup.py README.md ./
@@ -22,6 +20,12 @@ COPY . .
 
 RUN pip install .
 
+FROM python:3.10-slim
+COPY --from=builder $VIRTUAL_ENV $VIRTUAL_ENV
+ENV PATH="$VIRTUAL_ENV/bin:$PATH"
+
+WORKDIR /app
+
 EXPOSE 3000
 
 # Env variable for ISAR to know it is running in docker