refactor dockerfile so that we dont pip install from the top every time

Dockerfile-xmrauctions

@@ -2,13 +2,14 @@ FROM python:3
 
 RUN apt-get update
 RUN apt-get install python3 python3-venv -y
-RUN useradd -M -s /bin/bash -b /srv/xmrauctions xmrauctions
+COPY requirements.txt /tmp/requirements.txt
+RUN python3 -m venv /tmp/venv && /tmp/venv/bin/pip install -r /tmp/requirements.txt
 COPY . /srv/xmrauctions
+RUN cp -r /tmp/venv/ /srv/xmrauctions/.venv
+RUN useradd -s /bin/bash -d /srv/xmrauctions xmrauctions
 RUN chown -R xmrauctions:xmrauctions /srv/xmrauctions
-
+RUN chmod +x /srv/xmrauctions/bin/*
 USER xmrauctions
 WORKDIR /srv/xmrauctions
-RUN python3 -m venv .venv && . .venv/bin/activate && pip install -r requirements.txt
-RUN chmod +x ./bin/*
 
 ENTRYPOINT ["./bin/entrypoint"]