Add build dependencies to python_builder stage of Dockerfile

We've added django-qsessions. One of its dependencies is ua-parser-rs, a
Rust native extension. Our base image doesn't have have the required
toolchain to build this extension, so we add it to the python_builder
stage of the Dockerfile.

Author: malcolmbaig

Dockerfile

@@ -20,6 +20,8 @@ ARG poetry_version
 
 WORKDIR /app
 
+RUN apk add --no-cache libgcc libstdc++ build-base
+
 # Set environment variables
 ENV PYTHONDONTWRITEBYTECODE=1
 ENV PYTHONUNBUFFERED=1