Use conda-forge version of bilby.cython

This MR updates the dockerfiles to install bilby.cython from conda rather than pypi.

I verified that the images build properly in the CI, see here.

containers/dockerfile-template

@@ -54,8 +54,8 @@ RUN git clone https://github.com/jellis18/PTMCMCSampler.git \
 && (cd PTMCMCSampler && python setup.py install)
 
 # Install GW packages
-RUN conda install -n ${{conda_env}} -c conda-forge python-lalsimulation
-RUN pip install ligo-gracedb gwpy ligo.skymap bilby.cython
+RUN conda install -n ${{conda_env}} -c conda-forge python-lalsimulation bilby.cython
+RUN pip install ligo-gracedb gwpy ligo.skymap
 
 # Add the ROQ data to the image
 RUN mkdir roq_basis \