Pin basicpy version in pip install

This makes the version of the code installed in the container predictable
and stable. Ideally this Dockerfile should be part of the basicpy repo and
releases synchronized with the releases of basicpy itself, though.

Dockerfile

@@ -12,7 +12,7 @@ ENV PATH=/opt/conda/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:
 # Installing necessary packages
 
 # Installing basicpy and other pip packages
-RUN pip --no-cache-dir install git+https://github.com/peng-lab/BaSiCpy@dev bioformats_jar
+RUN pip --no-cache-dir install git+https://github.com/peng-lab/BaSiCpy@v1.2.0 bioformats_jar
 
 # Copy script and test run
 COPY ./main.py /opt/