[#161] Update the Dockerfile to support build with different hlink ex…

…tras

This should let us have two different test setups for each Python version. One
with xgboost, one without.

Dockerfile

@@ -1,5 +1,6 @@
 ARG PYTHON_VERSION=3.10
 FROM python:${PYTHON_VERSION}
+ARG HLINK_EXTRAS=dev
 
 RUN apt-get update && apt-get install default-jre-headless -y
 
@@ -8,4 +9,4 @@ WORKDIR /hlink
 
 COPY . .
 RUN python -m pip install --upgrade pip
-RUN pip install -e .[dev]
+RUN pip install -e .[${HLINK_EXTRAS}]