cleaning this up a little bit

Dockerfile

@@ -1,5 +1,7 @@
 FROM python:3.11-slim-bullseye
 
+ENV PIP_ROOT_USER_ACTION=ignore
+
 RUN apt-get -y update && apt-get upgrade -y && apt-get install -y unzip wget
 
 WORKDIR /opt/build
@@ -8,8 +10,7 @@ RUN /opt/build/install_pplacer.sh /usr/local
 
 COPY setup.py MANIFEST.in README.rst requirements.txt /opt/build/
 COPY taxtastic /opt/build/taxtastic/
-RUN python3 -m pip install --root-user-action=ignore --upgrade pip && \
-python3 -m pip install --constraint requirements.txt --root-user-action=ignore .
+RUN pip3 install --upgrade pip && pip3 install --requirement requirements.txt .
 
 WORKDIR /opt/run
 RUN mkdir -p /app /fh /mnt /run/shm