Add black Dockerfile

- Build a `black` container based on python3-slim
- Test: `docker build --network-host --tag black .`
```console
cooper-mbp1:black cooper$ docker image ls
REPOSITORY                                         TAG            IMAGE ID       CREATED              SIZE
black                                              latest         0c7636402ac2   4 seconds ago        332MB
```

Addresses part of #1914

Dockerfile

@@ -0,0 +1,10 @@
+FROM python:3-slim
+
+RUN pip install --upgrade pip setuptools wheel
+RUN apt update && apt install -y git
+RUN mkdir /src
+COPY . /src/
+RUN cd /src && pip install --no-cache-dir .
+RUN rm -rf /src && apt remove -y git && apt autoremove -y
+
+CMD ["black"]