Change pre-download target in Dockerfile

- `enterobacteria_phage` -> `yersinia_phage`

Author: moshi4

Dockerfile

@@ -9,7 +9,7 @@ RUN pip install -U pip && \
     pip install pygenomeviz[gui] --no-cache-dir
 
 # Download example dataset in advance
-RUN pgv-download enterobacteria_phage --cache_only && \
+RUN pgv-download yersinia_phage --cache_only && \
     pgv-download mycoplasma_mycoides --cache_only
 
 CMD ["/bin/bash"]