Remove git from Docker image

Since we use an archive url now, rather than git, we no longer need git to be installed.

Author: ChrisLovering

Dockerfile

@@ -4,11 +4,6 @@ FROM python:3.9-slim
 ENV PIP_NO_CACHE_DIR=false \
     POETRY_VIRTUALENVS_CREATE=false
 
-# Git is required to install a pinned version of d.py master
-RUN apt-get update && apt-get install -y \
-    git \
-    && rm -rf /var/lib/apt/lists/*
-
 # Install poetry
 RUN pip install -U poetry