Investigate: Issues moving Docker build to Alpine

[soup-bowl]

To improve size-efficiency I attempted to migrate the Docker image to Alpine. This worked well for AMD64, but appears to have a strange issue on ARM64. In both local tests and on GH Actions, the build takes ^10 mins to finish on ARM64. Aware that this is via QEMU, but this still appears to be incredibly slow.

The Dockerfile is:

FROM python:3-alpine

WORKDIR /opt/app

COPY htw                htw
COPY assets             assets
COPY requirements.txt   requirements.txt

RUN apk add python3-dev libc-dev zlib-dev jpeg-dev freetype-dev gcc \
	libxml2-dev libxslt-dev

RUN pip install --no-cache-dir -r requirements.txt

ENTRYPOINT [ "python", "-m", "htw" ]

Testing this on genuine ARM hardware should hopefully reveal what the true nature of the issue is.