Update Dockerfile.

Dockerfile

@@ -5,22 +5,14 @@ LABEL org.opencontainers.image.source=https://github.com/mareuter/lct-web
 LABEL org.opencontainers.image.description="Webservice for Lunar Club information."
 LABEL org.opencontainers.image.license=BSD-3-Clause
 
-WORKDIR /
-RUN  apt update && \
-     apt-get install --yes git && \
-     pip install --upgrade pip
-
 RUN adduser fastapi
 USER fastapi
 WORKDIR /home/fastapi
 
-COPY --chown=fastapi:fastapi pyproject.toml .
-COPY --chown=fastapi:fastpi .git .git
-COPY --chown=fastapi:fastapi src src
-
 ENV PATH="/home/fastapi/.local/bin:${PATH}"
 
-RUN pip install --user .
+RUN --mount=source=wheels,target=wheels,type=bind \
+    pip install --no-cache-dir --user wheels/*
 
 EXPOSE 8000