Merge branch 'master' of https://github.com/UBC-MDS/MCL-programming-in-python

Author: hfboyce

binder/Dockerfile

@@ -6,11 +6,12 @@ RUN pip install --no-cache --upgrade pip && \
                            "pytest>=4.4.1,<4.5.0" \
                            "black==19.10b0" \
                            "altair>=4.1.0" \
-                           "xlrd>=1.0.0" \
+                           "xlrd==1.2.0" \
                            "pandas==1.0.5" \
                            "plotly==4.8.1" \
                            "numpy>=1.11.0,<1.16.4" \
-                           "matplotlib==3.*"
+                           "matplotlib==3.*" \
+                           "openpyxl>=3.0.5"
 
 # create user with a home directory
 ARG NB_USER